Method and system for frequency up-conversion with modulation embodiments

ABSTRACT

A method and system is described wherein an information signals is gated at a frequency that is a sub-harmonic of the frequency of the desired output signal. In the modulation embodiments, the information signal is modulated as part of the up-conversion process. In a first modulation embodiment, one information signal is phase modulated onto the carrier signal as part of the up-conversion process. In a second modulation embodiment, two information signals are multiplied, and, as part of the up-conversion process, one signal is phase modulated onto the carrier and the other signal is amplitude modulated onto the carrier. In a third modulation embodiment, one information signal is phase modulated onto the “I” phase of the carrier signal as part of the up-conversion process and a second information signal is phase modulated onto the “Q” phase of the carrier as part of the up-conversion process. In a fourth modulation embodiment, four information signals are phase and amplitude modulated onto the “I” and “Q” phases of the carrier as part of the up-conversion process. There are at least two implementations of each of the aforementioned embodiments.

This is a continuation-in-part application of pending U.S. application“Method and System for Frequency Up-Conversion,” Ser. No. 09/379,497,filed Aug. 23, 999, which is a continuation of U.S. application “Methodand System for Frequency Up-Conversion,” Ser. No. 09/176,154, filed Oct.21, 1998, which are incorporated herein by reference in theirentireties.

CROSS-REFERENCE TO OTHER APPLICATIONS

The following applications of common assignee are related to the presentapplication, and are herein incorporated by reference in theirentireties:

“Method and System for Down-Converting Electromagnetic Signals,” Ser.No. 09/176,022, filed Oct. 21, 1998.

“Method and System for Ensuring Reception of a Communications Signal,”Ser. No. 09/176,415, filed Oct. 21, 1998.

“Integrated Frequency Translation and Selectivity,” Ser. No. 09/175,966,filed Oct. 21, 1998, U.S. Pat. No. 6,049,706.

“Applications of Universal Frequency Translation,” Ser. No. 09/261,129,filed Mar. 3, 1999.

“Method and System for Down-Converting Electromagnetic Signals HavingOptimized Switch Structures,” Ser. No. 09/293,095, filed Apr. 16, 1999.

“Method and System for Down-Converting Electromagnetic Signals IncludingResonant Structures for Enhanced Energy Transfer,” Ser. No. 09/293,342,filed Apr. 16, 1999.

“Method and System for Frequency Up-Conversion With a Variety ofTransmitter Configurations,” Ser. No. 09/293,580, filed Apr. 16, 1999.

“Integrated Frequency Translation And Selectivity With a Variety ofFilter Embodiments,” Ser. No. 09/293,283, filed Apr. 16, 1999.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is generally directed to frequency up-conversionof electromagnetic (EM) signals.

2. Related Art

Modern day communication systems employ components such as transmittersand receivers to transmit information from a source to a destination. Toaccomplish this transmission, information is imparted on a carriersignal and the carrier signal is then transmitted. Typically, thecarrier signal is at a frequency higher than the baseband frequency ofthe information signal. Typical ways that the information is imparted onthe carrier signal are called modulation.

Three widely used modulation schemes include: frequency modulation (FM),where the frequency of the carrier wave changes to reflect theinformation that has been modulated on the signal; phase modulation(PM), where the phase of the carrier signal changes to reflect theinformation imparted on it; and amplitude modulation (AM), where theamplitude of the carrier signal changes to reflect the information.Also, these modulation schemes are used in combination with each other(e.g., AM combined with FM and AM combined with PM).

SUMMARY OF THE INVENTION

The present invention is directed to methods and systems to up-convert asignal from a lower frequency to a higher frequency, and applicationsthereof.

In one embodiment, the invention uses a stable, low frequency signal togenerate a higher frequency signal with a frequency and phase that canbe used as stable references.

In another embodiment, the present invention is used as a transmitter.In this embodiment, the invention accepts an information signal at abaseband frequency and transmits a modulated signal at a frequencyhigher than the baseband frequency.

The methods and systems of transmitting vary slightly depending on themodulation scheme being used. For some embodiments using frequencymodulation (FM) or phase modulation (PM), the information signal is usedto modulate an oscillating signal to create a modulated intermediatesignal. If needed, this modulated intermediate signal is “shaped” toprovide a substantially optimum pulse-width-to-period ratio. This shapedsignal is then used to control a switch which opens and closes as afunction of the frequency and pulse width of the shaped signal. As aresult of this opening and closing, a signal that is harmonically richis produced with each harmonic of the harmonically rich signal beingmodulated substantially the same as the modulated intermediate signal.Through proper filtering, the desired harmonic (or harmonics) isselected and transmitted.

For some embodiments using amplitude modulation (AM), the switch iscontrolled by an unmodulated oscillating signal (which may, if needed,be shaped). As the switch opens and closes, it gates a reference signalwhich is the information signal. In an alternate implementation, theinformation signal is combined with a bias signal to create thereference signal, which is then gated. The result of the gating is aharmonically rich signal having a fundamental frequency substantiallyproportional to the oscillating signal and an amplitude substantiallyproportional to the amplitude of the reference signal. Each of theharmonics of the harmonically rich signal also have amplitudesproportional to the reference signal, and are thus considered to beamplitude modulated. Just as with the FM/PM embodiments described above,through proper filtering, the desired harmonic (or harmonics) isselected and transmitted.

Further features and advantages of the invention, as well as thestructure and operation of various embodiments of the invention, aredescribed in detail below with reference to the accompanying figures.The left-most digit(s) of a reference number typically identifies thefigure in which the reference number first appears.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates a circuit for a frequency modulation (FM)transmitter;

FIGS. 2A, 2B, and 2C illustrate typical waveforms associated with theFIG. 1 FM circuit for a digital information signal;

FIG. 3 illustrates a circuit for a phase modulation (PM) transmitter;

FIGS. 4A, 4B, and 4C illustrate typical waveforms associated with theFIG. 3 PM circuit for a digital information signal;

FIG. 5 illustrates a circuit for an amplitude modulation (AM)transmitter;

FIGS. 6A, 6B, and 6C illustrate typical waveforms associated with theFIG. 5 AM circuit for a digital information signal;

FIG. 7 illustrates a circuit for an in-phase/quadrature-phase modulation(“I/Q”) transmitter;

FIGS. 8A, 8B, 8C, 8D, and 8E illustrate typical waveforms associatedwith the FIG. 7 “I/Q” circuit for digital information signal;

FIG. 9 illustrates the high level operational flowchart of a transmitteraccording to an embodiment of the present invention;

FIG. 10 illustrates the high level structural block diagram of thetransmitter of an embodiment of the present invention;

FIG. 11 illustrates the operational flowchart of a first embodiment(i.e., FM mode) of the present invention;

FIG. 12 illustrates an exemplary structural block diagram of the firstembodiment (i.e., FM mode) of the present invention;

FIG. 13 illustrates the operational flowchart of a second embodiment(i.e., PM mode) of the present invention;

FIG. 14 illustrates an exemplary structural block diagram of the secondembodiment (i.e., PM mode) of the present invention;

FIG. 15 illustrates the operational flowchart of a third embodiment(i.e., AM mode) of the present invention;

FIG. 16 illustrates an exemplary structural block diagram of the thirdembodiment (i.e., AM mode) of the present invention;

FIG. 17 illustrates the operational flowchart of a fourth embodiment(i.e., “I/Q” mode) of the present invention;

FIG. 18 illustrates an exemplary structural block diagram of the fourthembodiment (i.e., “I/Q” mode) of the present invention;

FIGS. 19A-19I illustrate exemplary waveforms (for a frequency modulationmode operating in a frequency shift keying embodiment) at a plurality ofpoints in an exemplary high level circuit diagram;

FIGS. 20A, 20B, 20C illustrate typical waveforms associated with theFIG. 1 FM circuit for an analog information signal;

FIGS. 21A, 21B, 21C illustrate typical waveforms associated with theFIG. 3 PM circuit for an analog information signal;

FIGS. 22A, 22B, 22C illustrate typical waveforms associated with theFIG. 5 AM circuit for an analog information signal;

FIG. 23 illustrates an implementation example of a voltage controlledoscillator (VCO);

FIG. 24 illustrates an implementation example of a local oscillator(LO);

FIG. 25 illustrates an implementation example of a phase shifter;

FIG. 26 illustrates an implementation example of a phase modulator;

FIG. 27 illustrates an implementation example of a summing amplifier;

FIGS. 28A-28C illustrate an implementation example of a switch modulefor the FM and PM modes;

FIG. 29A-29C illustrate an example of the switch module of FIGS. 28A-28Cwherein the switch is a GaAsFET;

FIGS. 30A-30C illustrate an example of a design to ensure symmetry for aGaAsFET implementation in the FM and PM modes;

FIGS. 31A-31C illustrate an implementation example of a switch modulefor the AM mode;

FIGS. 32A-31C illustrate the switch module of FIGS. 31A-31C wherein theswitch is a GaAsFET;

FIGS. 33A-33C illustrates an example of a design to ensure symmetry fora GaAsFET implementation in the AM mode;

FIG. 34 illustrates an implementation example of a summer;

FIG. 35 illustrates an implementation example of a filter;

FIG. 36 is a representative spectrum demonstrating the calculation of“Q;”

FIGS. 37A and 37B are representative examples of filter circuits;

FIG. 38 illustrates an implementation example of a transmission module;

FIG. 39A shows a first exemplary pulse shaping circuit using digitallogic devices for a squarewave input from an oscillator;

FIGS. 39B, 39C, and 39D illustrate waveforms associated with the FIG.39A circuit;

FIG. 40A shows a second exemplary pulse shaping circuit using digitallogic devices for a squarewave input from an oscillator;

FIGS. 40B, 40C, and 40D illustrate waveforms associated with the FIG.40A circuit;

FIG. 41 shows a third exemplary pulse shaping circuit for any input froman oscillator;

FIGS. 42A, 42B, 42C, 42D, and 42E illustrate representative waveformsassociated with the FIG. 41 circuit;

FIG. 43 shows the internal circuitry for elements of FIG. 41 accordingto an embodiment of the invention;

FIGS. 44A-44G illustrate exemplary waveforms (for a pulse modulationmode operating in a pulse shift keying embodiment) at a plurality ofpoints in an exemplary high level circuit diagram, highlighting thecharacteristics of the first three harmonics;

FIGS. 45A-45F illustrate exemplary waveforms (for an amplitudemodulation mode operating in an amplitude shift keying embodiment) at aplurality of points in an exemplary high level circuit diagram,highlighting the characteristics of the first three harmonics;

FIG. 46 illustrates an implementation example of a harmonic enhancementmodule;

FIG. 47 illustrates an implementation example of an amplifier module;

FIGS. 48A and 48B illustrate exemplary circuits for a linear amplifier;

FIG. 49 illustrates a typical superheterodyne receiver;

FIG. 50 illustrates a transmitter according to an embodiment of thepresent invention in a transceiver circuit with a typicalsuperheterodyne receiver in a full-duplex mode;

FIGS. 51A, 51B, 51C, and 51D illustrate a transmitter according to anembodiment of the present invention in a transceiver circuit using acommon oscillator with a typical superheterodyne receiver in ahalf-duplex mode;

FIG. 52 illustrates an exemplary receiver using universal frequency downconversion techniques according to an embodiment;

FIG. 53 illustrates an exemplary transmitter of the present invention;

FIGS. 54A, 54B, and 54C illustrate an exemplary transmitter of thepresent invention in a transceiver circuit with a universal frequencydown conversion receiver operating in a half-duplex mode for the FM andPM modulation embodiment;

FIG. 55 illustrates an exemplary transmitter of the present invention ina transceiver circuit with a universal frequency down conversionreceiver operating in a half-duplex mode for the AM modulationembodiment;

FIG. 56 illustrates an exemplary transmitter of the present invention ina transceiver circuit with a universal frequency down conversionreceiver operating in a full-duplex mode;

FIGS. 57A-57C illustrate an exemplary transmitter of the presentinvention being used in frequency modulation, phase modulation, andamplitude modulation embodiments, including a pulse shaping circuit andan amplifier module;

FIG. 58 illustrates harmonic amplitudes for a pulse-width-to-periodratio of 0.01;

FIG. 59 illustrates harmonic amplitudes for a pulse-width-to-periodratio of 0.0556;

FIG. 60 is a table that illustrates the relative amplitudes of the first50 harmonics for six exemplary pulse-width-to-period ratios;

FIG. 61 is a table that illustrates the relative amplitudes of the first25 harmonics for six pulse-width-to-period ratios optimized for the1^(st) through 10^(th) subharmonics;

FIG. 62 illustrates an exemplary structural block diagram for analternative embodiment of the present invention (i.e., a mode wherein AMis combined with PM);

FIGS. 63A-63H illustrate exemplary waveforms (for the embodiment of FIG.62) at a plurality of points in an exemplary high level circuit diagram,highlighting the characteristics of the first two harmonics;

FIGS. 64A and 64A1 illustrate exemplary implementations of aliasingmodules;

FIGS. 64B-64F illustrate exemplary waveforms at a plurality of points inthe FIGS. 64A and 64A1 circuits;

FIG. 65—illustrates an exemplary circuit for a first implementation forphase modulating an information signal as part of the up-conversionprocess;

FIG. 66—illustrates an exemplary circuit for a first implementation forphase modulating one information signal and amplitude modulating asecond information signal as part of the up-conversion process;

FIG. 67—illustrates an exemplary circuit for a second implementation forphase modulating an information signal as part of the up-conversionprocess;

FIG. 68—illustrates an exemplary circuit for a second implementation forphase modulating one information signal and amplitude modulating asecond information signal as part of the up-conversion process;

FIG. 69—illustrates an exemplary circuit for a first implementation forphase modulating one information signal onto the “I” phase of a carrierand for phase modulating a second information signal onto the “Q” phaseof a carrier as part of the up-conversion process;

FIG. 70—illustrates an exemplary circuit for a second implementation forphase modulating one information signal onto the “I” phase of a carrierand for phase modulating a second information signal onto the “Q” phaseof a carrier as part of the up-conversion process;

FIG. 71—illustrates an exemplary circuit for phase modulating a firstinformation signal and amplitude modulating a second information signalonto the “I” phase of a carrier, and for phase modulating a thirdinformation signal and amplitude modulating a fourth information signalonto the “Q” phase of a carrier as part of the up-conversion process;

FIG. 72A is a block diagram of a splitter according to an embodiment ofthe invention;

FIG. 72B is a more detailed diagram of a splitter according to anembodiment of the invention;

FIGS. 72C and 72D are exemplary waveforms related to the splitter ofFIGS. 72A and 72B;

FIG. 72E is a block diagram of an I/Q circuit with a splitter accordingto an embodiment of the invention;

FIGS. 72F-72J are exemplary waveforms related to the diagram of FIG.72A;

FIG. 73 is a block diagram of a switch module according to an embodimentof the invention;

FIG. 74A is an implementation example of the block diagram of FIG. 73;

FIGS. 74B-74Q are exemplary waveforms related to FIG. 74A;

FIG. 75A is another implementation example of the block diagram of FIG.73;

FIGS. 75B-75Q are exemplary waveforms related to FIG. 75A;

FIG. 76A is an exemplary MOSFET embodiment of the invention;

FIG. 76B is an exemplary MOSFET embodiment of the invention;

FIG. 76C is an exemplary MOSFET embodiment of the invention;

FIG. 77A is another implementation example of the block diagram of FIG.73; and

FIGS. 77B-77Q are exemplary waveforms related to FIG. 75A.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Table of contents

-   1. Terminology.-   2. Overview of the Invention.    -   2.1 Discussion of Modulation Techniques.    -   2.2 Explanation of Exemplary Circuits and Waveforms.        -   2.2.1 Frequency Modulation.        -   2.2.2 Phase Modulation.        -   2.2.3 Amplitude Modulation.        -   2.2.4 In-phase/Quadrature-phase Modulation.    -   2.3 Features of the Invention.-   3. Frequency Up-conversion.    -   3.1 High Level Description.        -   3.1.1 Operational Description.        -   3.1.2 Structural Description.    -   3.2 Exemplary Embodiments.        -   3.2.1 First Embodiment: Frequency Modulation (FM) Mode.            -   3.2.1.1 Operational Description.            -   3.2.1.2 Structural Description.        -   3.2.2 Second Embodiment: Phase Modulation (PM) Mode.            -   3.2.2.1 Operational Description.            -   3.2.2.2 Structural Description.        -   3.2.3 Third Embodiment: Amplitude Modulation (AM) Mode.            -   3.2.3.1 Operational Description.            -   3.2.3.2 Structural Description.        -   3.2.4 Fourth Embodiment: In-phase/Quadrature-phase (“I/Q”)            Modulation Mode.            -   3.2.4.1 Operational Description.            -   3.2.4.2 Structural Description.        -   3.2.5 Other Embodiments.            -   3.2.5.1 Combination of Modulation Techniques            -   3.2.5.2 Modulation as Part of the Up-Conversion Process.    -   3.3 Methods and Systems for Implementing the Embodiments.        -   3.3.1 The Voltage Controlled Oscillator (FM Mode).            -   3.3.1.1 Operational Description.            -   3.3.1.2 Structural Description.        -   3.3.2 The Local Oscillator (PM, AM, and “I/Q” Modes).            -   3.3.2.1 Operational Description.            -   3.3.2.2 Structural Description.        -   3.3.3 The Phase Shifter (PM Mode).            -   3.3.3.1 Operational Description.            -   3.3.3.2 Structural Description.        -   3.3.4 The Phase Modulator (PM and “I/Q” Modes).            -   3.3.4.1 Operational Description.            -   3.3.4.2 Structural Description.        -   3.3.5 The Summing Module (AM Mode).            -   3.3.5.1 Operational Description.            -   3.3.5.2 Structural Description.        -   3.3.6 The Switch Module (FM, PM, and “I/Q” Modes).            -   3.3.6.1 Operational Description.            -   3.3.6.2 Structural Description.        -   3.3.7 The Switch Module (AM Mode).            -   3.3.7.1 Operational Description.            -   3.3.7.2 Structural Description.        -   3.3.8 The Summer (“I/Q” Mode).            -   3.3.8.1 Operational Description.            -   3.3.8.2 Structural Description.        -   3.3.9 The Filter (FM, PM, AM, and “I/Q” Modes).            -   3.3.9.1 Operational Description.            -   3.3.9.2 Structural Description.        -   3.3.10 The Transmission Module (FM, PM, AM, and “I/Q”            Modes).            -   3.3.10.1 Operational Description.            -   3.3.10.2 Structural Description.        -   3.3.11 Other Implementations.-   4. Harmonic Enhancement.    -   4.1 High Level Description.        -   4.1.1 Operational Description.        -   4.1.2 Structural Description.    -   4.2 Exemplary Embodiments.        -   4.2.1 First Embodiment: When a Square Wave Feeds the            Harmonic Enhancement Module to Create One Pulse per Cycle.            -   4.2.1.1 Operational Description.            -   4.2.1.2 Structural Description.        -   4.2.2 Second Embodiment: When a Square Wave Feeds the            Harmonic Enhancement Module to Create Two Pulses per Cycle.            -   4.2.2.1 Operational Description.            -   4.2.2.2 Structural Description.        -   4.2.3 Third Embodiment: When Any Waveform Feeds the Harmonic            Enhancement Module.            -   4.2.3.1 Operational Description.            -   4.2.3.2 Structural Description.        -   4.2.4 Other Embodiments.    -   4.3 Implementation Examples.        -   4.3.1 First Digital Logic Circuit.        -   4.3.2 Second Digital Logic Circuit.        -   4.3.3 Analog Circuit.        -   4.3.4 Other Implementations.-   5. Amplifier Module.    -   5.1 High Level Description.        -   5.1.1 Operational Description.        -   5.1.2 Structural Description.    -   5.2 Exemplary Embodiment.        -   5.2.1 Linear Amplifier.            -   5.2.1.1 Operational Description.            -   5.2.1.2 Structural Description.        -   5.2.2 Other Embodiments.    -   5.3 Implementation Examples.        -   5.3.1 Linear Amplifier.            -   5.3.1.1 Operational Description.            -   5.3.1.2 Structural Description.        -   5.3.2 Other Implementations.-   6. Receiver/Transmitter System.    -   6.1 High Level Description.    -   6.2 Exemplary Embodiments and Implementation Examples.        -   6.2.1 First Embodiment: The Transmitter of the Present            Invention Being Used in a Circuit with a Superheterodyne            Receiver.        -   6.2.2 Second Embodiment: The Transmitter of the Present            Invention Being Used with a Universal Frequency Down            Converter in a Half-Duplex Mode.        -   6.2.3 Third Embodiment: The Transmitter of the Present            Invention Being Used with a Universal Frequency Down            Converter in a Full-Duplex Mode.        -   6.2.4 Other Embodiments and Implementations.    -   6.3 Summary Description of Down-conversion Using a Universal        Frequency Translation Module.-   7. Designing a Transmitter According to an Embodiment of the Present    Invention.    -   7.1 Frequency of the Transmission Signal.    -   7.2 Characteristics of the Transmission Signal.    -   7.3 Modulation Scheme.    -   7.4 Characteristics of the Information Signal.    -   7.5 Characteristic of the Oscillating Signal.        -   7.5.1 Frequency of the Oscillating Signal.        -   7.5.2 Pulse Width of the String of Pulses.    -   7.6 Design of the Pulse Shaping Circuit.    -   7.7 Selection of the Switch.        -   7.7.1 Optimized Switch Structures.        -   7.7.2 Phased D2D—Splitter in CMOS    -   7.8 Design of the Filter.    -   7.9 Selection of an Amplifier.    -   7.10 Design of the Transmission Module.        1. Terminology.

Various terms used in this application are generally described in thissection. Each description in this section is provided for illustrativeand convenience purposes only, and is not limiting. The meaning of theseterms will be apparent to persons skilled in the relevant art(s) basedon the entirety of the teachings provided herein.

Amplitude Modulation (AM): A modulation technique wherein the amplitudeof the carrier signal is shifted (i.e., varied) as a function of theinformation signal. The frequency of the carrier signal typicallyremains constant. A subset of AM is referred to as “amplitude shiftkeying” which is used primarily for digital communications where theamplitude of the carrier signal shifts between discrete states ratherthan varying continuously as it does for analog information.

Analog signal: A signal in which the information contained therein iscontinuous as contrasted to discrete, and represents a time varyingphysical event or quantity. The information content is conveyed byvarying at least one characteristic of the signal, such as but notlimited to amplitude, frequency, or phase, or any combinations thereof.

Baseband signal: Any generic information signal desired for transmissionand/or reception. As used herein, it refers to both the informationsignal that is generated at a source prior to any transmission (alsoreferred to as the modulating baseband signal), and to the signal thatis to be used by the recipient after transmission (also referred to asthe demodulated baseband signal).

Carrier signal: A signal capable of carrying information. Typically, itis an electromagnetic signal that can be varied through a process calledmodulation. The frequency of the carrier signal is referred to as thecarrier frequency. A communications system may have multiple carriersignals at different carrier frequencies.

Control a switch: Causing a switch to open and close. The switch may be,without limitation, mechanical, electrical, electronic, optical, etc.,or any combination thereof. Typically, it is controlled by an electricalor electronic input. If the switch is controlled by an electronicsignal, it is typically a different signal than the signals connected toeither terminal of the switch.

Demodulated baseband signal: The baseband signal that is to be used bythe recipient after transmission. Typically it has been down convertedfrom a carrier signal and has been demodulated. The demodulated basebandsignal should closely approximate the information signal (i.e., themodulating baseband signal) in frequency, amplitude, and information.

Demodulation: The process of removing information from a carrier orintermediate frequency signal.

Digital signal: A signal in which the information contained therein hasdiscrete states as contrasted to a signal that has a property that maybe continuously variable.

Direct down conversion: A down conversion technique wherein a receivedsignal is directly down converted and demodulated, if applicable, fromthe original transmitted frequency (i.e., a carrier frequency) tobaseband without having an intermediate frequency.

Down conversion: A process for performing frequency translation in whichthe final frequency is lower than the initial frequency.

Drive a switch: Same as control a switch.

Frequency Modulation (FM): A modulation technique wherein the frequencyof the carrier signal is shifted (i.e., varied) as a function of theinformation signal. A subset of FM is referred to as “frequency shiftkeying” which is used primarily for digital communications where thefrequency of the carrier signal shifts between discrete states ratherthan varying continuously as it does for analog information.

Harmonic: A harmonic is a frequency or tone that, when compared to itsfundamental or reference frequency or tone, is an integer multiple ofit. In other words, if a periodic waveform has a fundamental frequencyof “f” (also called the first harmonic), then its harmonics may belocated at frequencies of “n·f,” where “n” is 2, 3, 4, etc. The harmoniccorresponding to n=2 is referred to as the second harmonic, the harmoniccorresponding to n=3 is referred to as the third harmonic, and so on.

In-phase (“I”) signal: The signal typically generated by an oscillator.It has not had its phase shifted and is often represented as a sine waveto distinguish it from a “Q” signal. The “I” signal can, itself, bemodulated by any means. When the “I” signal is combined with a signal,the resultant signal is referred to as an “I/Q” signal.

In-phase/Quadrature-phase (“I/Q”) signal: The signal that results whenan “I” signal is summed with a “Q” signal. Typically, both the “I” and“Q” signals have been phase modulated, although other modulationtechniques may also be used, such as amplitude modulation. An “I/Q”signal is used to transmit separate streams of informationsimultaneously on a single transmitted carrier. Note that the modulated“I” signal and the modulated “Q” signal are both carrier signals havingthe same frequency. When combined, the resultant “I/Q” signal is also acarrier signal at the same frequency.

Information signal: The signal that contains the information that is tobe transmitted. As used herein, it refers to the original basebandsignal at the source. When it is intended that the information signalmodulate a carrier signal, it is also referred to as the “modulatingbaseband signal.” It may be voice or data, analog or digital, or anyother signal or combination thereof.

Intermediate frequency (IF) signal: A signal that is at a frequencybetween the frequency of the baseband signal and the frequency of thetransmitted signal.

Modulation: The process of varying one or more physical characteristicsof a signal to represent the information to be transmitted. Threecommonly used modulation techniques are frequency modulation, phasemodulation, and amplitude modulation. There are also variations,subsets, and combinations of these three techniques.

Operate a switch: Same as control a switch.

Phase Modulation (PM): A modulation technique wherein the phase of thecarrier signal is shifted (i.e., varied) as a function of theinformation signal. A subset of PM is referred to as “phase shiftkeying” which is used primarily for digital communications where thephase of the carrier signal shifts between discrete states rather thanvarying continuously as it does for analog information.

Quadrature-phase (“Q”) signal: A signal that is out of phase with anin-phase (“I”)-signal. The amount of phase shift is predetermined for aparticular application, but in a typical implementation, the “Q” signalis 90° out of phase with the “I” signal. Thus, if the “I” signal were asine wave, the “Q” signal would be a cosine wave. When discussedtogether, the “I” signal and the “Q” signal have the same frequencies.

Spectrum: Spectrum is used to signify a continuous range of frequencies,usually wide, within which electromagnetic (EM) waves have some specificcommon characteristic. Such waves may be propagated in any communicationmedium, both natural and manmade, including but not limited to air,space, wire, cable, liquid, waveguide, microstrip, stripline, opticalfiber, etc. The EM spectrum includes all frequencies greater than zerohertz.

Subharmonic: A subharmonic is a frequency or tone that is an integersubmultiple of a referenced fundamental frequency or tone. That is, asubharmonic frequency is the quotient obtained by dividing thefundamental frequency by an integer. For example, if a periodic waveformhas a frequency of “f” (also called the “fundamental frequency” or firstsubharmonic), then its subharmonics have frequencies of “f/n,” where nis 2, 3, 4, etc. The subharmonic corresponding to n=2 is referred to asthe second subharmonic, the subharmonic corresponding to n=3 is referredto as the third subharmonic, and so on. A subharmonic itself haspossible harmonics, and the i^(th) harmonic of the i^(th) subharmonicwill be at the fundamental frequency of the original periodic waveform.For example, the third subharmonic (which has a frequency of “f/3”) mayhave harmonics at integer multiples of itself (i.e., a second harmonicat “2·f/3,” a third harmonic at “3·f/3,” and so on). The third harmonicof the third subharmonic of the original signal (i.e., “3·f/3”) is atthe frequency of the original signal.

Trigger a switch: Same as control a switch.

Up conversion: A process for performing frequency translation in whichthe final frequency is higher than the initial frequency.

2. Overview of the Invention.

The present invention is directed to systems and methods for frequencyup-conversion, and applications thereof.

In one embodiment, the frequency up-converter of the present inventionis used as a stable reference frequency source in a phase comparator orin a frequency comparator. This embodiment of the present inventionachieves this through the use of a stable, low frequency localoscillator, a switch, and a filter. Because it up-converts frequency,the present invention can take advantage of the relatively low cost oflow frequency oscillators to generate stable, high frequency signals.

In a second embodiment, the frequency up-converter is used as a systemand method for transmitting an electromagnetic (EM) signal.

Based on the discussion contained herein, one skilled in the relevantart(s) will recognize that there are other, alternative embodiments inwhich the frequency up-converter of the present invention could be usedin other applications, and that these alternative embodiments fallwithin the scope of the present invention.

For illustrative purposes, various modulation examples are discussedbelow. However, it should be understood that the invention is notlimited by these examples. Other modulation techniques that might beused with the present invention will be apparent to persons skilled inthe relevant art(s) based on the teaching contained herein.

Also for illustrative purposes, frequency up-conversion according to thepresent invention is described below in the context of a transmitter.However, the invention is not limited to this embodiment. Equivalents,extensions, variations, deviations, etc., of the following will beapparent to persons skilled in the relevant art(s) based on theteachings contained herein. Such equivalents, extensions, variations,deviations, etc., are within the scope and spirit of the presentinvention.

2.1 Discussion of Modulation Techniques.

Techniques by which information can be imparted onto EM signals to betransmitted are called modulation. These techniques are generally wellknown to one skilled in the relevant art(s), and include, but are notlimited to, frequency modulation (FM), phase modulation (PM), amplitudemodulation (AM), quadrature-phase shift keying (QPSK), frequency shiftkeying (FSK), phase shift keying (PSK), amplitude shift keying (ASK),etc., and combinations thereof. These last three modulation techniques,FSK, PSK, and ASK, are subsets of FM, PM, and AM, respectively, andrefer to circuits having discrete input signals (e.g., digital inputsignals).

For illustrative purposes only, the circuits and techniques describedbelow all refer to the EM broadcast medium. However, the invention isnot limited by this embodiment. Persons skilled in the relevant art(s)will recognize that these same circuits and techniques can be used inall transmission media (e.g., over-the-air broadcast, point-to-pointcable, etc.).

2.2 Explanation of Exemplary Circuits and Waveforms.

2.2.1 Frequency Modulation.

FIG. 1 illustrates an example of a frequency modulation (FM) circuit 100and FIGS. 2A, 2B, and 2C, and FIGS. 20A, 20B, and 20C illustrateexamples of waveforms at several points in FM circuit 100. In an FMsystem, the frequency of a carrier signal, such as an oscillating signal202 (FIG. 2B and FIG. 20B), is varied to represent the data to becommunicated, such as information signals 102 of FIGS. 2A and 2002 ofFIG. 20A. In FIG. 20A, information signal 2002 is a continuous signal(i.e., an analog signal), and in FIG. 2A, information signal 102 is adiscrete signal (i.e., a digital signal). In the case of the discreteinformation signal 102, the FM circuit 100 is referred to as a frequencyshift keying (FSK) system, which is a subset of an FM system.

Frequency modulation circuit 100 receives an information signal 102,2002 from a source (not shown). Information signal 102, 2002 can beamplified by an optional amplifier 104 and filtered by an optionalfilter 114 and is the voltage input that drives a voltage controlledoscillator (VCO) 106. Within VCO 106, an oscillating signal 202 (seen onFIG. 2B and FIG. 20B) is generated. The purpose of VCO 106 is to varythe frequency of oscillating signal 202 as a function of the inputvoltage, i.e., information signal 102, 2002. The output of VCO 106 is amodulated signal shown as modulated signal 108 (FIG. 2C) when theinformation signal is the digital information signal 102 and shown asmodulated signal 2004 (FIG. 20C) when the information signal is theanalog signal 2002. Modulated signal 108, 2004 is at a relatively lowfrequency (e.g., generally between 50 MHz and 100 MHz) and can have itsfrequency increased by an optional frequency multiplier 110 (e.g., to900 MHz, 1.8 GHz) and have its amplitude increased by an optionalamplifier 116. The output of optional frequency multiplier 110 and/oroptional amplifier 116 is then transmitted by an exemplary antenna 112.

2.2.2 Phase Modulation.

FIG. 3 illustrates an example of a phase modulation (PM) circuit 300 andFIGS. 4A, 4B, and 4C, and FIGS. 21A, 21B, and 21C illustrate examples ofwaveforms at several points in PM circuit 300. In a PM system, the phaseof a carrier signal, such as a local oscillator (LO) output 308 (FIG. 4Band FIG. 21B), is varied to represent the data to be communicated, suchas an information signals 302 of FIGS. 4A and 2102 of FIG. 21A. In FIG.21A, information signal 2102 is a continuous signal (i.e., an analogsignal), and in FIG. 4A, information signal 302 is a discrete signal(i.e., a digital signal). In the case of the discrete information signal302, the PM circuit is referred to as a phase shift keying (PSK) system.This is the typical implementation, and is a subset of a PM system.

Phase modulation circuit 300 receives information signal 302, 2102 froma source (not shown). Information signal 302, 2102 can be amplified byan optional amplifier 304 and filtered by an optional filter 318 and isrouted to a phase modulator 306. Also feeding phase modulator 306 is LOoutput 308 of a local oscillator 310. LO output 308 is shown on FIG. 4Band FIG. 21B. Local oscillators, such as local oscillator 310, output anelectromagnetic wave at a predetermined frequency and amplitude.

The output of phase modulator 306 is a modulated signal shown as a phasemodulated signal 312 (FIG. 4C) when the information signal is thediscrete information signal 302 and shown as a phase modulated signal2104 (FIG. 21C) when the information signal is the analog informationsignal 2102. The purpose of phase modulator 306 is to change the phaseof LO output 308 as a function of the value of information signal 302,2102. That is, for example in a PSK mode, if LO output 308 were a sinewave, and the value of information signal 302 changed from a binary highto a binary low, the phase of LO output 308 would change from a sinewave with a zero phase to a sine wave with, for example, a phase of180°. The result of this phase change would be phase modulated signal312 of FIG. 4C which would have the same frequency as LO output 308, butwould be out of phase by 180° in this example. For a PSK system, thephase changes in phase modulated signal 312 that are representative ofthe information in information signal 302 can be seen by comparingwaveforms 302, 308, and 312 on FIGS. 4A, 4B, and 4C. For the case of ananalog information signal 2102 of FIG. 21A, the phase of LO output 308of FIG. 21B changes continuously as a function of the amplitude of theinformation signal 2102. That is, for example, as information signal2102 increases from a value of “X” to “X+δx”, the PM signal 2104 of FIG.21C changes from a signal which may be represented by the equationsin(ωt) to a signal which can be represented by the equation sin(ωt+φ),where φ is the phase change associated with a change of δx ininformation signal 2102. For an analog PM system, the phase changes inphase modulated signal 2104 that are representative of the informationin information signal 2102 can be seen by comparing waveforms 2102, 308,and 2104 on FIGS. 21A, 21B, and 21C.

After information signal 302, 2102 and LO output 308 have been modulatedby phase modulator 306, phase modulated signal 312, 2104 can be routedto an optional frequency multiplier 314 and optional amplifier 320. Thepurpose of optional frequency multiplier 314 is to increase thefrequency of phase modulated signal 312 from a relatively low frequency(e.g., 50 MHz to 100 MHz) to a desired broadcast frequency (e.g., 900MHz, 1.8 GHz). Optional amplifier 320 raises the signal strength ofphase modulated signal 312, 2104 to a desired level to be transmitted byan exemplary antenna 316.

2.2.3 Amplitude Modulation.

FIG. 5 illustrates an example of an amplitude modulation (AM) circuit500 and FIGS. 6A, 6B, and 6C, and FIGS. 22A, 22B, and 22C illustrateexamples of waveforms at several points in AM circuit 500. In an AMsystem, the amplitude of a carrier signal, such as a local oscillator(LO) signal 508 (FIG. 6B and FIG. 22B), is varied to represent the datato be communicated, such as information signals 502 of FIGS. 6A and 2202of FIG. 22A. In FIG. 22A, information signal 2202 is a continuous signal(i.e., an analog signal), and in FIG. 6A, information signal 502 is adiscrete signal (i.e., a digital signal). In the case of the discreteinformation signal 502, the AM circuit is referred to as an amplitudeshift keying (ASK) system, which is a subset of an AM system.

Amplitude modulation circuit 500 receives information signal 502 from asource (not shown). Information signal 502, 2202 can be amplified by anoptional amplifier 504 and filtered by an optional filter 518. Amplitudemodulation circuit 500 also includes a local oscillator (LO) 506 whichhas an LO output 508. Information signal 502, 2202 and LO output 508 arethen multiplied by a multiplier 510. The purpose of multiplier 510 is tocause the amplitude of LO output 508 to vary as a function of theamplitude of information signal 502, 2202. The output of multiplier 510is a modulated signal shown as amplitude modulated signal 512 (FIG. 6C)when the information signal is the digital information signal 502 andshown as modulated signal 2204 (FIG. 22C) when the information signal isthe analog information signal 2202. AM signal 512, 2204 can then berouted to an optional frequency multiplier 514 where the frequency of AMsignal 512, 2204 is increased from a relatively low level (e.g., 50 MHzto 100 MHz) to a higher level desired for broadcast (e.g., 900 MHz, 1.8GHz) and an optional amplifier 520, which increases the signal strengthof AM signal 512, 2204 to a desired level for broadcast by an exemplaryantenna 516.

2.2.4 In-phase/Quadrature-phase Modulation.

FIG. 7 illustrates an example of an in-phase/quadrature-phase (“I/Q”)modulation circuit 700 and FIGS. 8A, 8B, 8C, 8D, and 8E illustrateexamples of waveforms at several points in “I/Q” modulation circuit 700.In this technique, which increases bandwidth efficiency, separateinformation signals can be simultaneously transmitted on carrier signalsthat are out of phase with each other. That is, a first informationsignal 702 of FIG. 8A can be modulated onto the in-phase (“I”)oscillator signal 710 of FIG. 8B and a second information signal 704 ofFIG. 8C can be modulated onto the quadrature-phase (“Q”) oscillatorsignal 712 of FIG. 8D. The “I” modulated signal is combined with the “Q”modulated signal and the resulting “I/Q” modulated signal is thentransmitted. In a typical usage, both information signals are digital,and both are phase modulated onto the “I” and “Q” oscillating signals.One skilled in the relevant art(s) will recognize that the “I/Q” modecan also work with analog information signals, with combinations ofanalog and digital signals, with other modulation techniques, or anycombinations thereof.

This “I/Q” modulation system uses two PM circuits together in order toincrease the bandwidth efficiency. As stated above, in a PM circuit, thephase of an oscillating signal, such as 710 (or 712) (FIG. 8B or 8D), isvaried to represent the data to be communicated, such as an informationsignal such as 702 (or 704). For ease of understanding and display, thediscussion herein will describe the more typical use of the “I/Q” mode,that is, with digital information signals and phase modulation on bothoscillating signals. Thus, both signal streams are phase shift keying(PSK), which is a subset of PM.

“I/Q” modulation circuit 700 receives an information signal 702 from afirst source (not shown) and an information signal 704 from a secondsource (not shown). Examples of information signals 702 and 704 areshown in FIGS. 8A and 8C. Information signals 702 and 704 can beamplified by optional amplifiers 714 and 716 and filtered by optionalfilters 734 and 736. It is then routed to phase modulators 718 and 720.Also feeding phase modulators 718 and 720 are oscillating signals 710and 712. Oscillating signal 710 was generated by a local oscillator 706,and is shown in FIG. 8B, and oscillating signal 712 is the phase shiftedoutput of local oscillator 706. Local oscillators, such as localoscillator 706, output an electromagnetic wave at a predeterminedfrequency and amplitude.

The output of phase modulator 718 is a phase modulated signal 722 whichis shown using a dotted line as one of the waveforms in FIG. 8E.Similarly, the output of phase modulator 720, which operates in a mannersimilar to phase modulator 718, is a phase modulated signal 724 which isshown using a solid line as the other waveform in FIG. 8E. The effect ofphase modulators 718 and 720 on oscillating signals 710 and 712 is tocause them to change phase. As stated above, the system shown here is aPSK system, and as such, the phase of oscillating signals 710 and 712 isshifted by phase modulators 718 and 720 by a discrete amount as afunction of information signals 702 and 704.

For simplicity of discussion and ease of display, oscillating signal 710is shown on FIG. 8B as a sine wave and is referred to as the “I” signalin the “I/Q” circuit 700. After the output of oscillator 706 has gonethrough a phase shifter 708, shown here as shifting the phase by −π/2,oscillating signal 712 is a cosine wave, shown on FIG. 8D, and isreferred to as the “Q” signal in the “I/Q” circuit. Again, for ease ofdisplay, phase modulators 718 and 720 are shown as shifting the phase ofthe respective oscillating signals 710 and 712 by 180°. This is seen onFIG. 8E. Modulated signal 722 is summed with modulated signal 724 by asummer 726. The output of summer 726 is the arithmetic sum of modulatedsignal 722 and 724 and is an “I/Q” signal 728. (For clarity of thedisplay on FIG. 8E, the combined signal 728 is not shown. However, oneskilled in the relevant art(s) will recognize that the arithmetic sum of2 sinusoidal waves having the same frequency is also a sinusoidal waveat that frequency.)

“I/Q” signal 728 can then be routed to an optional frequency multiplier730, where the frequency of “I/Q” signal 718 is increased from arelatively low level (e.g., 50 MHz to 100 MHz) to a higher level desiredfor broadcast (e.g., 900 MHz, 1.8 GHz), and to an optional amplifier 738which increases the signal strength of “I/Q” signal 728 to a desiredlevel for broadcast by an exemplary antenna 732.

2.3 Features of the Invention.

As apparent from the above, several frequencies are involved in acommunications system. The frequency of the information signal isrelatively low. The frequency of the local oscillator (both the voltagecontrolled oscillator as well as the other oscillators) is higher thanthat of the information signal, but typically not high enough forefficient transmission. A third frequency, not specifically mentionedabove, is the frequency of the transmitted signal which is greater thanor equal to the frequency of the oscillating signal. This is thefrequency that is routed from the optional frequency multipliers andoptional amplifiers to the antennas in the previously describedcircuits.

Typically, in the transmitter subsystem of a communications system,upconverting the information signal to broadcast frequency requires, atleast, filters, amplifiers, and frequency multipliers. Each of thesecomponents is costly, not only in terms of the purchase price of thecomponent, but also because of the power required to operate them.

The present invention provides a more efficient means for producing amodulated carrier for transmission, uses less power, and requires fewercomponents. These and additional advantages of the present inventionwill be apparent from the following description.

3. Frequency Up-conversion.

The present invention is directed to systems and methods for frequencyup-conversion and applications of the same. In one embodiment, thefrequency up-converter of the present invention allows the use of astable, low frequency oscillator to generate a stable high frequencysignal that, for example and without limitation, can be used as areference signal in a phase comparator or a frequency comparator. Inanother embodiment, the up-converter of the present invention is used ina transmitter. The invention is also directed to a transmitter. Based onthe discussion contained herein, one skilled in the relevant art(s) willrecognize that there are other, alternative embodiments and applicationsin which the frequency up-converter of the present invention could beused, and that these alternative embodiments and applications fallwithin the scope of the present invention.

For illustrative purposes, frequency up-conversion according to thepresent invention is described below in the context of a transmitter.However, as apparent from the preceding paragraph, the invention is notlimited to this embodiment.

The following sections describe methods related to a transmitter andfrequency up-converter. Structural exemplary embodiments for achievingthese methods are also described. It should be understood that theinvention is not limited to the particular embodiments described below.Equivalents, extensions, variations, deviations, etc., of the followingwill be apparent to persons skilled in the relevant art(s) based on theteachings contained herein. Such equivalents, extensions, variations,deviations, etc., are within the scope and spirit of the presentinvention.

3.1. High Level Description.

This section (including its subsections) provides a high-leveldescription of up-converting and transmitting signals according to thepresent invention. In particular, an operational process of frequencyup-conversion in the context of transmitting signals is described at ahigh-level. The operational process is often represented by flowcharts.The flowcharts are presented herein for illustrative purposes only, andare not limiting. In particular, the use of flowcharts should not beinterpreted as limiting the invention to discrete or digital operation.In practice, those skilled in the relevant art(s) will appreciate, basedon the teachings contained herein, that the invention can be achievedvia discrete operation, continuous operation, or any combinationthereof. Furthermore, the flow of control represented by the flowchartsis also provided for illustrative purposes only, and it will beappreciated by persons skilled in the relevant art(s) that otheroperational control flows are within the scope and spirit of theinvention.

Also, a structural implementation for achieving this process isdescribed at a high-level. This structural implementation is describedherein for illustrative purposes, and is not limiting. In particular,the process described in this section can be achieved using any numberof structural implementations, one of which is described in thissection. The details of such structural implementations will be apparentto persons skilled in the relevant art(s) based on the teachingscontained herein.

3.1.1 Operational Description.

The flow chart 900 of FIG. 9 demonstrates the operational method offrequency up-conversion in the context of transmitting a signalaccording to an embodiment of the present invention. The invention isdirected to both frequency up-conversion and transmitting signals asrepresented in FIG. 9. Representative waveforms for signals generated inflow chart 900 are depicted in FIG. 19. For purposes of illustrating thehigh level operation of the invention, frequency modulation of a digitalinformation signal is depicted. The invention is not limited to thisexemplary embodiment. One skilled in the relevant art(s) will appreciatethat other modulation modes could alternatively be used (as described inlater sections).

In step 902, an information signal 1902 (FIG. 19A) is generated by asource. This information signal may be analog, digital, and anycombination thereof, or anything else that is desired to be transmitted,and is at the baseband frequency. As described below, the informationsignal 1902 is used to modulate an intermediate signal 1904.Accordingly, the information signal 1902 is also herein called amodulating baseband information signal. In the example of FIG. 19A, theinformation signal 1902 is illustrated as a digital signal. However, theinvention is not limited to this embodiment. As noted above, theinformation signal 1902 can be analog, digital, and/or any combinationthereof.

An oscillating signal 1904 (FIG. 19B) is generated in step 904. In step906, the oscillating signal 1904 is modulated, where the modulation is aresult of, and a function of, the information signal 1902. Step 906produces a modulated oscillating signal 1906 (FIG. 19C), also called amodulated intermediate signal. As noted above, the flowchart of FIG. 9is being described in the context of an example where the informationsignal 1902 is a digital signal. However, alternatively, the informationsignal 1902 can be analog or any combination of analog and digital.Also, the example shown in FIG. 19 uses frequency shift keying (FSK) asthe modulation technique. Alternatively, any modulation technique (e.g.,FM, AM, PM, ASK, PSK, etc., or any combination thereof) can be used. Theremaining steps 908-912 of the flowchart of FIG. 9 operate in the sameway, whether the information signal 1902 is digital, analog, etc., orany combination thereof, and regardless of what modulation technique isused.

A harmonically rich signal 1908 (FIG. 19D) is generated from themodulated signal 1906 in step 908. Signal 1908 has a substantiallycontinuous and periodically repeated waveform. In an embodiment, thewaveform of signal 1908 is substantially rectangular, as is seen in theexpanded waveform 1910 of FIG. 19E. One skilled in the relevant art(s)will recognize the physical limitations to and mathematical obstaclesagainst achieving an exact or perfect rectangular waveform and it is notthe intent or requirement of the present invention that a perfectrectangular waveform be generated or needed. However, for ease ofdiscussion, the term “rectangular waveform” will be used herein and willrefer to waveforms that are substantially rectangular, and will includebut will not be limited to those waveforms that are generally referredto as square waves or pulses. It should be noted that if the situationarises wherein a perfect rectangular waveform is proven to be bothtechnically and mathematically feasible, that situation will also fallwithin the scope and intent of this invention.

A continuous periodic waveform (such as waveform 1908) is composed of aseries of sinusoidal waves of specific amplitudes and phases, thefrequencies of which are integer multiples of the repetition frequencyof the waveform. (A waveform's repetition frequency is the number oftimes per second the periodic waveform repeats.) A portion of thewaveform of signal 1908 is shown in an expanded view as waveform 1910 ofFIG. 19E. The first three sinusoidal components of waveform 1910 (FIG.19E) are depicted as waveforms 1912 a, b, & c of FIG. 19F and waveforms1914 a, b, & c of FIG. 19G. (In the examples of FIGS. 19F & G, the threesinusoidal components are shown separately. In actuality, thesewaveforms, along with all the other sinusoidal components which are notshown, occur simultaneously, as seen in FIG. 19H. Note that in FIG. 19H,the waveforms are shown simultaneously, but are not shown summed. Ifwaveforms 1912 and 1914 were shown summed, they would, in the limit,i.e., with an infinite number of sinusoidal components, be identical tothe periodic waveform 1910 of FIG. 19E. For ease of illustration, onlythe first three of the infinite number of sinusoidal components areshown.) These sinusoidal waves are called harmonics, and their existencecan be demonstrated both graphically and mathematically. Each harmonic(waveforms 1912 a, b, & c and 1914 a, b, & c) has the same informationcontent as does waveform 1910 (which has the same information as thecorresponding portion of waveform 1908). Accordingly, the informationcontent of waveform 1908 can be obtained from any of its harmonics. Asthe harmonics have frequencies that are integer multiples of therepetition frequency of signal 1908, and since they have the sameinformation content as signal 1908 (as just stated), the harmonics eachrepresent an up-converted representation of signal 1908. Some of theharmonics are at desired frequencies (such as the frequencies desired tobe transmitted). These harmonics are called “desired harmonics” or“wanted harmonics.” According to the invention, desired harmonics havesufficient amplitude for accomplishing the desired processing (i.e.,being transmitted). Other harmonics are not at the desired frequencies.These harmonics are called “undesired harmonics” or “unwantedharmonics.”

In step 910, any unwanted harmonics of the continuous periodic waveformof signal 1908 are filtered out (for example, any harmonics that are notat frequencies desired to be transmitted). In the example of FIG. 19,the first and second harmonics (i.e., those depicted by waveforms 1912 a& b of FIGS. 19F and 1914 a & b of FIG. 19G) are the unwanted harmonics.In step 912, the remaining harmonic, in the example of FIG. 19, thethird harmonic (i.e., those depicted by waveforms 1912 c of FIGS. 19Fand 1914 c of FIG. 19G), is transmitted. This is depicted by waveform1918 of FIG. 19I. In the example of FIG. 19, only three harmonics areshown, and the lowest two are filtered out to leave the third harmonicas the desired harmonic. In actual practice, there are an infinitenumber of harmonics, and the filtering can be made to remove unwantedharmonics that are both lower in frequency than the desired harmonic aswell as those that are higher in frequency than the desired harmonic.

3.1.2 Structural Description.

FIG. 10 is a block diagram of an up-conversion system according to anembodiment of the invention. This embodiment of the up-conversion systemis shown as a transmitter 1000. Transmitter 1000 includes an acceptancemodule 1004, a harmonic generation and extraction module 1006, and atransmission module 1008 that accepts an information signal 1002 andoutputs a transmitted signal 1014.

Preferably, the acceptance module 1004, harmonic generation andextraction module 1006, and transmission module 1008 process theinformation signal in the manner shown in the operational flowchart 900.In other words, transmitter 1000 is the structural embodiment forperforming the operational steps of flowchart 900. However, it should beunderstood that the scope and spirit of the present invention includesother structural embodiments for performing the steps of flowchart 900.The specifics of these other structural embodiments will be apparent topersons skilled in the relevant art(s) based on the discussion containedherein.

The operation of the transmitter 1000 will now be described in detailwith reference to the flowchart 900. In step 902, an information signal1002 (for example, see FIG. 19A) from a source (not shown) is routed toacceptance module 1004. In step 904, an oscillating signal (for example,see FIG. 19B) is generated and in step 906, it is modulated, therebyproducing a modulated signal 1010 (for an example of FM, see FIG. 19C).The oscillating signal can be modulated using any modulation technique,examples of which are described below. In step 908, the harmonicgeneration and extraction module (HGEM) generates a harmonically richsignal with a continuous and periodic waveform (an example of FM can beseen in FIG. 19D). This waveform is preferably a rectangular wave, suchas a square wave or a pulse (although, the invention is not limited tothis embodiment), and is comprised of a plurality of sinusoidal waveswhose frequencies are integer multiples of the fundamental frequency ofthe waveform. These sinusoidal waves are referred to as the harmonics ofthe underlying waveform. A Fourier series analysis can be used todetermine the amplitude of each harmonic (for example, see FIGS. 19F and19G). In step 910, a filter (not shown) within HGEM 1006 filters out theundesired frequencies (harmonics), and outputs an electromagnetic (EM)signal 1012 at the desired frequency (for example, see FIG. 19I). Instep 912, EM signal 1012 is routed to transmission module 1008(optional), where it is prepared for transmission. The transmissionmodule 1008 then outputs a transmitted signal 1014.

3.2 Exemplary Embodiments.

Various embodiments related to the method(s) and structure(s) describedabove are presented in this section (and its subsections). Theseembodiments are described herein for purposes of illustration, and notlimitation. The invention is not limited to these embodiments. Alternateembodiments (including equivalents, extensions, variations, deviations,etc., of the embodiments described herein) will be apparent to personsskilled in the relevant art(s) based on the teachings contained herein.The invention is intended and adapted to include such alternateembodiments.

3.2.1 First Embodiment: Frequency Modulation (FM) Mode.

In this embodiment, an information signal is accepted and a modulatedsignal whose frequency varies as a function of the information signalresults.

3.2.1.1 Operational Description.

The flow chart of FIG. 11 demonstrates the method of operation of atransmitter in the frequency modulation (FM) mode according to anembodiment of the present invention. As stated above, the representativewaveforms shown in FIG. 19 depict the invention operating as atransmitter in the FM mode.

In step 1102, an information signal 1902 (FIG. 19A) is generated by asource by any means and/or process. (Information signal 1902 is abaseband signal, and, because it is used to modulate a signal, may alsobe referred to as a modulating baseband signal 1902.) Information signal1902 may be, for example, analog, digital, or any combination thereof.The signals shown in FIG. 19 depict a digital information signal whereinthe information is represented by discrete states of the signal. It willbe apparent to persons skilled in the relevant art(s) that the inventionis also adapted to working with an analog information signal wherein theinformation is represented by a continuously varying signal. In step1104, information signal 1902 modulates an oscillating signal 1904 (FIG.19B). The result of this modulation is the modulated signal 1906 (FIG.19C) as indicated in block 1106. Modulated signal 1906 has a frequencythat varies as a function of information signal 1902 and is referred toas an FM signal.

In step 1108, a harmonically rich signal with a continuous periodicwaveform, shown in FIG. 19D as rectangular waveform 1908, is generated.Rectangular waveform 1908 is generated using the modulated signal 1906.One skilled in the relevant art(s) will recognize the physicallimitations to and mathematical obstacles against achieving an exact orperfect rectangular waveform and it is not the intent of the presentinvention that a perfect rectangular waveform be generated or needed.Again, as stated above, for ease of discussion, the term “rectangularwaveform” will be used to refer to waveforms that are substantiallyrectangular. In a similar manner, the term “square wave” will refer tothose waveforms that are substantially square and it is not the intentof the present invention that a perfect square wave be generated orneeded. A portion of rectangular waveform 1908 is shown in an expandedview as periodic waveform 1910 in FIG. 19E. The first part of waveform1910 is designated “signal A” and represents information signal 1902being “high,” and the second part of waveform 1910 is designated “signalB” and information signal 1902 being “low.” It should be noted that thisconvention is used for illustrative purposes only, and alternatively,other conventions could be used.

As stated before, a continuous and periodic waveform, such as arectangular wave 1908 as indicated in block 1110 of flowchart 1100, hassinusoidal components (harmonics) at frequencies that are integermultiples of the fundamental frequency of the underlying waveform (i.e.,at the Fourier component frequencies). Three harmonics of periodicwaveform 1910 are shown separately, in expanded views, in FIGS. 19F and19G. Since waveform 1910 (and also waveform 1908) is shown as a squarewave in this exemplary embodiment, only the odd harmonics are present,i.e., the first, third, fifth, seventh, etc. As shown in FIG. 19, ifrectangular waveform 1908 has a fundamental frequency of f, (also knownas the first harmonic), the third harmonic will have a frequency of3·f₁, the fifth harmonic will have a frequency of 5·f₁, and so on. Thefirst, third, and fifth harmonics of signal A are shown as waveforms1912 a, 1912 b, and 1912 c of FIG. 19F, and the first, third, and fifthharmonics of signal B are shown as waveforms 1914 a, 1914 b, and 1914 cof FIG. 19G. In actuality, these harmonics (as well as all of the higherorder harmonics) occur simultaneously, as shown by waveform 1916 of FIG.19H. Note that if all of the harmonic components of FIG. 19H were shownsummed together with all of the higher harmonics (i.e., the seventh, theninth, etc.) the resulting waveform would, in the limit, be identical towaveform 1910.

In step 1112, the unwanted frequencies of waveform 1916 are removed. Inthe example of FIG. 19, the first and third harmonics are shown to beremoved, and as indicated in block 1114, the remaining waveform 1918(i.e., waveforms 1912 c and 1914 c) is at the desired EM frequency.Although not shown, the higher harmonics (e.g., the seventh, ninth,etc.) are also removed.

The EM signal, shown here as remaining waveform 1918, is prepared fortransmission in step 1116, and in step 1118, the EM signal istransmitted.

3.2.1.2 Structural Description.

FIG. 12 is a block diagram of a transmitter according to an embodimentof the invention. This embodiment of the transmitter is shown as an FMtransmitter 1200. FM transmitter 1200 includes a voltage controlledoscillator (VCO) 1204, a switch module 1214, a filter 1218, and atransmission module 1222 that accepts an information signal 1202 andoutputs a transmitted signal 1224. The operation and structure ofexemplary components are described below: an exemplary VCO is describedbelow at sections 3.3.1-3.3.1.2; an exemplary switch module is describedbelow at sections 3.3.6-3.3.6.2; an exemplary filter is described belowat sections 3.3.9-3.3.9.2; and an exemplary transmission module isdescribed below at sections 3.3.10-3.3.10.2.

Preferably, the voltage controlled oscillator 1204, switch module 1214,filter 1218, and transmission module 1222 process the information signalin the manner shown in the operational flowchart 1100. In other words,FM transmitter 1200 is the structural embodiment for performing theoperational steps of flowchart 1100. However, it should be understoodthat the scope and spirit of the present invention includes otherstructural embodiments for performing the steps of flowchart 1100. Thespecifics of these other structural embodiments will be apparent topersons skilled in the relevant art(s) based on the discussion containedherein.

The operation of the transmitter 1200 will now be described in detailwith reference to the flowchart 1100. In step 1102, an informationsignal 1202 (for example, see FIG. 19A) from a source (not shown) isrouted to VCO 1204. In step 1104, an oscillating signal (for example,see FIG. 19B) is generated and modulated, thereby producing a frequencymodulated signal 1210 (for example, see FIG. 19C). In step 1108, theswitch module 1214 generates a harmonically rich signal 1216 with acontinuous and periodic waveform (for example, see FIG. 19D). Thiswaveform is preferably a rectangular wave, such as a square wave or apulse (although, the invention is not limited to this embodiment), andis comprised of a plurality of sinusoidal waves whose frequencies areinteger multiples of the fundamental frequency of the waveform. Thesesinusoidal waves are referred to as the harmonics of the underlyingwaveform, and a Fourier analysis will determine the amplitude of eachharmonic (for example, see FIGS. 19F and 19G). In step 1112, a filter1218 filters out the undesired frequencies (harmonics), and outputs anelectromagnetic (EM) signal 1220 at the desired harmonic frequency (forexample, see FIG. 191). In step 1116, EM signal 1220 is routed totransmission module 1222 (optional), where it is prepared fortransmission. In step 1118, transmission module 1222 outputs atransmitted signal 1224.

3.2.2 Second Embodiment: Phase Modulation (PM) Mode.

In this embodiment, an information signal is accepted and a modulatedsignal whose phase varies as a function of the information signal istransmitted.

3.2.2.1 Operational Description.

The flow chart of FIG. 13 demonstrates the method of operation of thetransmitter in the phase modulation (PM) mode. The representativewaveforms shown in FIG. 44 depict the invention operating as atransmitter in the PM mode.

In step 1302, an information signal 4402 (FIG. 44A) is generated by asource. Information signal 4402 may be, for example, analog, digital, orany combination thereof. The signals shown in FIG. 44 depict a digitalinformation signal wherein the information is represented by discretestates of the signal. It will be apparent to persons skilled in therelevant art(s) that the invention is also adapted to working with ananalog information signal wherein the information is represented by acontinuously varying signal. In step 1304, an oscillating signal 4404 isgenerated and in step 1306, the oscillating signal 4404 (FIG. 44B) ismodulated by the information signal 4402, resulting in the modulatedsignal 4406 (FIG. 44C) as indicated in block 1308. The phase of thismodulated signal 4406 is varied as a function of the information signal4402.

A harmonically rich signal 4408 (FIG. 44D) with a continuous periodicwaveform is generated at step 1310 using modulated signal 4406.Harmonically rich signal 4408 is a substantially rectangular waveform.One skilled in the relevant art(s) will recognize the physicallimitations to and mathematical obstacles against achieving an exact orperfect rectangular waveform and it is not the intent of the presentinvention that a perfect rectangular waveform be generated or needed.Again, as stated above, for ease of discussion, the term “rectangularwaveform” will be used to refer to waveforms that are substantiallyrectangular. In a similar manner, the term “square wave” will refer tothose waveforms that are substantially square and it is not the intentof the present invention that a perfect square wave be generated orneeded. As stated before, a continuous and periodic waveform, such asthe harmonically rich signal 4408 as indicated in block 1312, hassinusoidal components (harmonics) at frequencies that are integermultiples of the fundamental frequency of the underlying waveform (theFourier component frequencies). The first three harmonic waveforms areshown in FIGS. 44E, 44F, and 44G. In actual fact, there are an infinitenumber of harmonics. In step 1314, the unwanted frequencies are removed,and as indicated in block 1316, the remaining frequency is at thedesired EM output. As an example, the first (fundamental) harmonic 4410and the second harmonic 4412 along with the fourth, fifth, etc.,harmonics (not shown) might be filtered out, leaving the third harmonic4414 as the desired EM signal as indicated in block 1316.

The EM signal is prepared for transmission in step 1318, and in step1320, the EM signal is transmitted.

3.2.2.2 Structural Description.

FIG. 14 is a block diagram of a transmitter according to an embodimentof the invention. This embodiment of the transmitter is shown as a PMtransmitter 1400. PM transmitter 1400 includes a local oscillator 1406,a phase modulator 1404, a switch module 1410, a filter 1414, and atransmission module 1418 that accepts an information signal 1402 andoutputs a transmitted signal 1420. The operation and structure ofexemplary components are described below: an exemplary phase modulatoris described below at sections 3.3.4-3.3.4.2; an exemplary localoscillator is described below at sections 3.3.2-3.3.2.2; an exemplaryswitch module is described below at sections 3.3.6-3.3.6.2; an exemplaryfilter is described below at sections 3.3.9-3.3.9.2; and an exemplarytransmission module is described below at sections 3.3.10-3.3.10.2.

Preferably, the local oscillator 1406, phase modulator 1404, switchmodule 1410, filter 1414, and transmission module 1418 process theinformation signal in the manner shown in the operational flowchart1300. In other words, PM transmitter 1400 is the structural embodimentfor performing the operational steps of flowchart 1300. However, itshould be understood that the scope and spirit of the present inventionincludes other structural embodiments for performing the steps offlowchart 1300. The specifics of these other structural embodiments willbe apparent to persons skilled in the relevant art(s) based on thediscussion contained herein.

The operation of the transmitter 1400 will now be described in detailwith reference to the flowchart 1300. In step 1302, an informationsignal 1402 (for example, see FIG. 44A) from a source (not shown) isrouted to phase modulator 1404. In step 1304, an oscillating signal fromlocal oscillator 1406 (for example, see FIG. 44B) is generated andmodulated, thereby producing a modulated signal 1408 (for example, seeFIG. 44C). In step 1310, the switch module 1410 generates a harmonicallyrich signal 1412 with a continuous and periodic waveform (for example,see FIG. 44D). This waveform is preferably a rectangular wave, such as asquare wave or a pulse (although, the invention is not limited to thisembodiment), and is comprised of a plurality of sinusoidal waves whosefrequencies are integer multiples of the fundamental frequency of thewaveform. These sinusoidal waves are referred to as the harmonics of theunderlying waveform, and a Fourier analysis will determine the amplitudeof each harmonic (for an example of the first three harmonics, see FIGS.44E, 44F, and 44G). In step 1314, a filter 1414 filters out theundesired harmonic frequencies (for example, the first harmonic 4410,the second harmonic 4412, and the fourth, fifth, etc., harmonics, notshown), and outputs an electromagnetic (EM) signal 1416 at the desiredharmonic frequency (for example, the third harmonic, see FIG. 44G). Instep 1318, EM signal 1416 is routed to transmission module 1418(optional), where it is prepared for transmission. In step 1320, thetransmission module 1418 outputs a transmitted signal 1420.

3.2.3 Third Embodiment: Amplitude Modulation (AM) Mode.

In this embodiment, an information signal is accepted and a modulatedsignal whose amplitude varies as a function of the information signal istransmitted.

3.2.3.1 Operational Description.

The flow chart of FIG. 15 demonstrates the method of operation of thetransmitter in the amplitude modulation (AM) mode. The representativewaveforms shown in FIG. 45 depict the invention operating as atransmitter in the AM mode.

In step 1502, an information signal 4502 (FIG. 45A) is generated by asource. Information signal 4502 may be, for example, analog, digital, orany combination thereof. The signals shown in FIG. 45 depict a digitalinformation signal wherein the information is represented by discretestates of the signal. It will be apparent to persons skilled in therelevant art(s) that the invention is also adapted to working with ananalog information signal wherein the information is represented by acontinuously varying signal. In step 1504, a “reference signal” iscreated, which, as indicated in block 1506, has an amplitude that is afunction of the information signal 4502. In one embodiment of theinvention, the reference signal is created by combining the informationsignal 4502 with a bias signal. In another embodiment of the invention,the reference signal is comprised of only the information signal 4502.One skilled in the relevant art(s) will recognize that any number ofembodiments exist wherein the reference signal will vary as a functionof the information signal.

An oscillating signal 4504 (FIG. 45B) is generated at step 1508, and atstep 1510, the reference signal (information signal 4502) is gated at afrequency that is a function of the oscillating signal 4504. The gatedreferenced signal is a harmonically rich signal 4506 (FIG. 45C) with acontinuous periodic waveform and is generated at step 1512. Thisharmonically rich signal 4506 as indicated in block 1514 issubstantially a rectangular wave which has a fundamental frequency equalto the frequency at which the reference signal (information signal 4502)is gated. In addition, the rectangular wave has pulse amplitudes thatare a function of the amplitude of the reference signal (informationsignal 4502). One skilled in the relevant art(s) will recognize thephysical limitations to and mathematical obstacles against achieving anexact or perfect rectangular waveform and it is not the intent of thepresent invention that a perfect rectangular waveform be generated orneeded. Again, as stated above, for ease of discussion, the term“rectangular waveform” will be used to refer to waveforms that aresubstantially rectangular. In a similar manner, the term “square wave”will refer to those waveforms that are substantially square and it isnot the intent of the present invention that a perfect square wave begenerated or needed.

As stated before, a harmonically rich signal 4506, such as therectangular wave as indicated in block 1514, has sinusoidal components(harmonics) at frequencies that are integer multiples of the fundamentalfrequency of the underlying waveform (the Fourier componentfrequencies). The first three harmonic waveforms are shown in FIGS. 45D,45E, and 45F. In fact, there are an infinite number of harmonics. Instep 1516, the unwanted frequencies are removed, and as indicated inblock 1518, the remaining frequency is at the desired EM output. As anexample, the first (fundamental) harmonic 4510 and the second harmonic4512 along with the fourth, fifth, etc., harmonics (not shown) might befiltered out leaving the third harmonic 4514 as the desired EM signal asindicated in block 1518.

The EM signal is prepared for transmission in step 1520, and in step1522, the EM signal is transmitted.

3.2.3.2 Structural Description.

FIG. 16 is a block diagram of a transmitter according to an embodimentof the invention. This embodiment of the transmitter is shown as an AMtransmitter 1600. AM transmitter 1600 includes a local oscillator 1610,a summing module 1606, a switch module 1614, a filter 1618, and atransmission module 1622 that accepts an information signal 1602 andoutputs a transmitted signal 1624. The operation and structure ofexemplary components are described below: an exemplary local oscillatoris described below at sections 3.3.2-3.3.2.2; an exemplary a switchmodule is described below at sections 3.3.7-3.3.7.2; an exemplary filteris described below at sections 3.3.9-3.3.9.2; and an exemplarytransmission module is described below at sections 3.3.10-3.3.10.2.

Preferably, the local oscillator 1610, summing module 1606, switchmodule 1614, filter 1618, and transmission module 1622 process aninformation signal 1602 in the manner shown in the operational flowchart1500. In other words, AM transmitter 1600 is the structural embodimentfor performing the operational steps of flowchart 1500. However, itshould be understood that the scope and spirit of the present inventionincludes other structural embodiments for performing the steps offlowchart 1500. The specifics of these other structural embodiments willbe apparent to persons skilled in the relevant art(s) based on thediscussion contained herein.

The operation of the transmitter 1600 will now be described in detailwith reference to the flowchart 1500. In step 1502, information signal1602 (for example, see FIG. 45A) from a source (not shown) is routed tosumming module 1606 (if required), thereby producing a reference signal1608. In step 1508, an oscillating signal 1612 is generated by localoscillator 1610 (for example, see FIG. 45B) and in step 1510, switchmodule 1614 gates the reference voltage 1608 at a rate that is afunction of the oscillating signal 1612. The result of the gating is aharmonically rich signal 1616 (for example, see FIG. 45C) with acontinuous and periodic waveform. This waveform is preferably arectangular wave, such as a square wave or a pulse (although, theinvention is not limited to this embodiment), and is comprised of aplurality of sinusoidal waves whose frequencies are integer multiples ofthe fundamental frequency of the waveform. These sinusoidal waves arereferred to as the harmonics of the underlying waveform, and a Fourieranalysis will determine the relative amplitude of each harmonic (for anexample of the first three harmonics, see FIGS. 45D, 45E, and 45F). Whenamplitude modulation is applied, the amplitude of the pulses inrectangular waveform 1616 vary as a function of reference signal 1608.As a result, this change in amplitude of the pulses has a proportionaleffect on the absolute amplitude of all of the harmonics. In otherwords, the AM is embedded on top of each of the harmonics. In step 1516,a filter 1618 filters out the undesired harmonic frequencies (forexample, the first harmonic 4510, the second harmonic 4512, and thefourth, fifth, etc., harmonics, not shown), and outputs anelectromagnetic (EM) signal 1620 at the desired harmonic frequency (forexample, the third harmonic, see FIG. 45F). In step 1520, EM signal 1620is routed to transmission module 1622 (optional), where it is preparedfor transmission. In step 1522, the transmission module 1622 outputs atransmitted signal 1624.

Note that the description of the AM embodiment given herein shows theinformation signal being gated, thus applying the amplitude modulationto the harmonically rich signal. However, is would be apparent based onthe teachings contained herein, that the information signal can bemodulated onto the harmonically rich signal or onto a filtered harmonicat any point in the circuit.

3.2.4 Fourth Embodiment: In-phase/Quadrature-phase Modulation (“I/Q”)Mode.

In-phase/quadrature-phase modulation (“[/Q”) is a specific subset of aphase modulation (PM) embodiment. Because “I/Q” is so pervasive, it isdescribed herein as a separate embodiment. However, it should beremembered that since it is a specific subset of PM, the characteristicsof PM also apply to “I/Q.”

In this embodiment, two information signals are accepted. An in-phasesignal (“I”) is modulated such that its phase varies as a function ofone of the information signals, and a quadrature-phase signal (“Q”) ismodulated such that its phase varies as a function of the otherinformation signal. The two modulated signals are combined to form an“I/Q” modulated signal and transmitted.

3.2.4.1 Operational Description.

The flow chart of FIG. 17 demonstrates the method of operation of thetransmitter in the in-phase/quadrature-phase modulation (“I/Q”) mode. Instep 1702, a first information signal is generated by a first source.This information signal may be analog, digital, or any combinationthereof. In step 1710, an in-phase oscillating signal (referred to asthe “I” signal) is generated and in step 1704, it is modulated by thefirst information signal. This results in the “I” modulated signal asindicated in block 1706 wherein the phase of the “I” modulated signal isvaried as a function of the first information signal.

In step 1714, a second information signal is generated. Again, thissignal may be analog, digital, or any combination thereof, and may bedifferent than the first information signal. In step 1712, the phase of“I” oscillating signal generated in step 1710 is shifted, creating aquadrature-phase oscillating signal (referred to as the “Q” signal). Instep 1716, the “Q” signal is modulated by the second information signal.This results in the “Q” modulated signal as indicated in block 1718wherein the phase of the “Q” modulated signal is varied as a function ofthe second information signal.

An “I” signal with a continuous periodic waveform is generated at step1708 using the “I” modulated signal, and a “Q” signal with a continuousperiodic waveform is generated at step 1720 using the “Q” modulatedsignal. In step 1722, the “I” periodic waveform and the “Q” periodicwaveform are combined forming what is referred to as the “I/Q” periodicwaveform as indicated in block 1724. As stated before, a continuous andperiodic waveform, such as a “I/Q” rectangular wave as indicated inblock 1724, has sinusoidal components (harmonics) at frequencies thatare integer multiples of the fundamental frequency of the underlyingwaveform (the Fourier component frequencies). In step 1726, the unwantedfrequencies are removed, and as indicated in block 1728, the remainingfrequency is at the desired EM output.

The “I/Q” EM signal is prepared for transmission in step 1730, and instep 1732, the “I/Q” EM signal is transmitted.

3.2.4.2 Structural Description.

FIG. 18 is a block diagram of a transmitter according to an embodimentof the invention. This embodiment of the transmitter is shown as an“I/Q” transmitter 1800. “I/Q” transmitter 1800 includes a localoscillator 1806, a phase shifter 1810, two phase modulators 1804 & 1816,two switch modules 1822 & 1828, a summer 1832, a filter 1836, and atransmission module 1840. The “I/Q” transmitter accepts two informationsignals 1802 & 1814 and outputs a transmitted signal 1420. The operationand structure of exemplary components are described below: an exemplaryphase modulator is described below at sections 3.3.4-3.3.4.2; anexemplary local oscillator is described below at sections 3.3.2-3.3.2.2;an exemplary phase shifter is described below at sections 3.3.3-3.3.3.2;an exemplary switch module is described below at sections 3.3.6-3.3.6.2;an exemplary summer is described below at sections 3.3.8-3.3.8.2; anexemplary filter is described below at sections 3.3.9-3.3.9.2; and anexemplary transmission module is described below at sections3.3.10-3.3.10.2.

Preferably, the local oscillator 1806, phase shifter 1810, phasemodulators 1804 & 1816, switch modules 1822 & 1828, summer 1832, filter1836, and transmission module 1840 process the information signal in themanner shown in the operational flowchart 1700. In other words, “I/Q”transmitter 1800 is the structural embodiment for performing theoperational steps of flowchart 1700. However, it should be understoodthat the scope and spirit of the present invention includes otherstructural embodiments for performing the steps of flowchart 1700. Thespecifics of these other structural embodiments will be apparent topersons skilled in the relevant art(s) based on the discussion containedherein.

The operation of the transmitter 1800 will now be described in detailwith reference to the flowchart 1700 In step 1702, a first informationsignal 1802 from a source (not shown) is routed to the first phasemodulator 1804. In step 1710, an “I” oscillating signal 1808 from localoscillator 1806 is generated and in step 1704, “I” oscillating signal1808 is modulated by first information signal 1802 in the first phasemodulator 1804, thereby producing an “I” modulated signal 1820. In step1708, the first switch module 1822 generates a harmonically rich “I”signal 1824 with a continuous and periodic waveform.

In step 1714, a second information signal 1814 from a source (not shown)is routed to the second phase modulator 1816. In step 1712, the phase ofoscillating signal 1808 is shifted by phase shifter 1810 to create “Q”oscillating signal 1812. In step 1716, “Q” oscillating signal 1812 ismodulated by second information signal 1814 in the second phasemodulator 1816, thereby producing “Q” modulated signal 1826. In step1720, the second switch module 1828 generates a harmonically rich “Q”signal 1830 with a continuous and periodic waveform. Harmonically rich“I” signal 1824 and harmonically rich “Q” signal 1830 are preferablyrectangular waves, such as square waves or pulses (although, theinvention is not limited to this embodiment), and are comprised ofpluralities of sinusoidal waves whose frequencies are integer multiplesof the fundamental frequency of the waveforms. These sinusoidal wavesare referred to as the harmonics of the underlying waveforms, and aFourier analysis will determine the amplitude of each harmonic.

In step 1722, harmonically rich “I” signal 1824 and harmonically rich“Q” signal 1830 are combined by summer 1832 to create harmonically rich“I/Q” signal 1834. In step 1726, a filter 1836 filters out the undesiredharmonic frequencies, and outputs an “I/Q” electromagnetic (EM) signal1838 at the desired harmonic frequency. In step 1730, “I/Q” EM signal1838 is routed to transmission module 1840 (optional), where it isprepared for transmission. In step 1732, the transmission module 1840outputs a transmitted signal 1842.

It will be apparent to those skilled in the relevant art(s) that analternate embodiment exists wherein the harmonically rich “I” signal1824 and the harmonically rich “Q” signal 1830 may be filtered beforethey are summed, and further, another alternate embodiment existswherein “I” modulated signal 1820 and “Q” modulated signal 1826 may besummed to create an “I/Q” modulated signal before being routed to aswitch module.

3.2.5 Other Embodiments.

Other embodiments of the up-converter of the present invention beingused as a transmitter (or in other applications) may use subsets andcombinations of modulation techniques, and may include modulating one ormore information signals as part of the up-conversion process.

3.2.5.1 Combination of Modulation Techniques

Combinations of modulation techniques that would be apparent to thoseskilled in the relevant art(s) based on the teachings disclosed hereininclude, but are not limited to, quadrature amplitude modulation (QAM),and embedding two forms of modulation onto a signal for up-conversion.

An exemplary circuit diagram illustrating the combination of twomodulations is found in FIG. 62. This example uses AM combined with PM.The waveforms shown in FIG. 63 illustrate the phase modulation of adigital information signal “A” 6202 combined with the amplitudemodulation of an analog information signal “B” 6204. An oscillatingsignal 6216 (FIG. 63B) and information signal “A” 6202 (FIG. 63A) arereceived by phase modulator 1404, thereby creating a phase modulatedsignal 6208 (FIG. 63C). Note that for illustrative purposes, and notlimiting, the information signal is shown as a digital signal, and thephase modulation is shown as shifting the phase of the oscillatingsignal by 180°. Those skilled in the relevant art(s) will appreciatethat the information signal could be analog (although typically it isdigital), and that phase modulations other than 180° may also be used.FIG. 62 shows a pulse shaper 6216 receiving phase modulated signal 6208and outputting a pulse-shaped PM signal 6210. The pulse shaper isoptional, depending on the selection and design of the phase modulator1404. Information signal “B” 6304 and bias signal 1604 (if required) arecombined by summing module 1606 (optional) to create reference signal6206 (FIG. 63E). Pulse-shaped PM signal 6210 is routed to switch module1410, 1614 where it gates the reference signal 6206 thereby producing aharmonically rich signal 6212 (FIG. 63F). It can be seen that theamplitude of harmonically rich signal 6212 varies as a function ofreference signal 6206, and the period and pulse width of harmonicallyrich signal 6212 are substantially the same as pulse-shaped PM signal6210. FIG. 63 only illustrates the fundamental and second harmonics ofharmonically rich signal 6212. In fact, there may be an infinite numberof harmonics, but for illustrative purposes (and not limiting) the firsttwo harmonics are sufficient to illustrate that both the phasemodulation and the amplitude modulation that are present on theharmonically rich signal 6212 are also present on each of the harmonics.Filter 1414, 1618 will remove the unwanted harmonics, and a desiredharmonic 6214 is routed to transmission module 1418, 1622 (optional)where it is prepared for transmission. Transmission module 1418, 1622then outputs a transmitted signal 1420, 1624. Those skilled in therelevant art(s) will appreciate that these examples are provided forillustrative purposes only and are not limiting.

The embodiments described above are provided for purposes ofillustration. These embodiments are not intended to limit the invention.Alternate embodiments, differing slightly or substantially from thosedescribed herein, will be apparent to persons skilled in the relevantart(s) based on the teachings contained herein. Such alternateembodiments include, but are not limited to, combinations of modulationtechniques in an “I/Q” mode. Such alternate embodiments fall within thescope and spirit of the present invention.

3.2.5.2 Modulation as Part of the Up-Conversion Process.

Alternate embodiments of the present invention include implementationswherein one or more information signals are modulated as part of theup-conversion process. For ease of discussion, these implementationswill be referred to as “modulation embodiments” and will be discussed inmore detail below.

In a first modulation embodiment, one information signal is phasemodulated onto the carrier signal as part of the up-conversion process.Two exemplary implementations of this modulation embodiment are hereindescribed. One involves using a differentiation circuit and the otherinvolves using parallel switches that are controlled by signals that are180° out of phase with each other.

In a second modulation embodiment, two information signals aremultiplied. As part of the up-conversion process, one signal is phasemodulated onto the carrier and the other signal is amplitude modulatedonto the carrier. Again, as described in the first modulation embodimentabove, two exemplary implementations of this modulation embodiment areherein described.

In a third modulation embodiment, one information signal is phasemodulated onto the “I” phase of the carrier signal as part of theup-conversion process and a second information signal is phase modulatedonto the “Q” phase of the carrier as part of the up-conversion process.As described above, two exemplary implementations of this modulationembodiment are herein described.

In a fourth modulation embodiment, a first information signal ismultiplied with a second information signal, and the result is modulatedonto the “I” phase of a carrier as part of the up-conversion process.The first information signal is phase modulated and the secondinformation signal is amplitude modulated. Additionally, a thirdinformation signal is multiplied with a fourth information signal, andthe result is modulated onto the “Q” phase of a carrier as part of theup-conversion process. The third information signal is phased modulatedand the fourth information signal is amplitude modulated. As describedabove, two exemplary implementations of this modulation embodiment areherein described.

It is noted that the exemplary implementations are described herein forillustrative purposes only. The invention is not limited to theseexamples. Other implementations will be apparent to persons skilled inthe relevant art(s) based on the teachings contained herein.

One exemplary implementation of the first modulation embodiment is shownin FIG. 65. An information signal 6502 is routed through an optionalfilter 6504. This results in a filtered information signal 6522.Typically, information signal 6502 (as well as filtered informationsignal 6522) is a digital signal, although the invention may work withanalog signals. Filtered information signal 6522 is connected through aload, shown as an inductor 6506, to the first input of a switch 6512.The second input of switch 6512 is connected to a reference 6514. In oneimplementation, reference 6514 is at ground and, in a secondimplementation, reference 6514 is at a non-zero voltage.

A local oscillator 6508 generates an oscillating signal 6526. Thefrequency of oscillating signal 6526 is a sub-harmonic of the desiredoutput frequency of the up-converter. Oscillating signal 6526 is routedthrough a pulse shaper 6510. Pulse shaper 6510 is optional, and, whenused, outputs a string of pulses 6528. String of pulses 6528 isconnected to the control input of switch 6512, and controls thefrequency at which switch 6512 closes and opens.

The first input of switch 6512 is also connected to the input of adifferentiation circuit 6516. Differentiation circuit 6516 is shown asbeing comprised of a capacitor 6518 in series and a resistor 6520shunted to ground. This circuit diagram is shown for illustrativepurposes only, and persons skilled in the relevant art(s) willappreciate that other differentiating circuits may be used. The outputof differentiation circuit 6516 is a harmonically rich signal 6524 thatis phase modulated. Harmonically rich signal 6524 is comprised of aplurality of harmonics and is routed to a filter 6530. Filter 6530extracts one or more of the harmonics as desired output signal 6532.

A second exemplary implementation of the first modulation embodiment isshown in FIG. 67. An information signal 6702 is routed through anoptional filter 6704. This results in a filtered information signal6708. Typically, information signal 6702 (as well as filteredinformation signal 6708) is a digital signal, although the invention maywork with analog signals. Filtered information signal 6708 is connectedto a buffer/inverter module 6706. Buffer/inverter module 6706 outputs abuffered information signal 6710 and an inverted information signal6712. Buffered information signal 6710 is substantially the same asfiltered information signal 6708 and inverted information signal 6712 issubstantially equal to the inverse of buffered information signal 6710.A number of circuits, such as off-the-shelf buffers and off-the-shelfinverters, or customer designed buffers and inverters, can be used toaccomplish the function of buffer/inverter module 6706, as can beappreciated by those skilled in the relevant art(s).

Buffered information signal 6710 is then routed through a load, shown asan inductor 6730, to the first input of a switch 6726, and invertedinformation signal 6712 is routed through a load, shown as an inductor6732, to the first input of a switch 6728. The second input of switch6726 and the second input of switch 6728 are connected to a reference6746. As shown in FIG. 67, the second input of switch 6726 and thesecond input of switch 6728 are connected to the same reference 6746.Those skilled in the relevant art(s) will understand that this does notneed to be the same reference. In one implementation, reference 6746 isat ground and in another implementation reference 6746 is at a non-zerovoltage.

A local oscillator 6714 generates an oscillating signal 6716. Thefrequency of oscillating signal 6716 is preferably an odd sub-harmonicof the desired output frequency of the up-converter. Oscillating signal6716 is routed through a 180° phase shifter 6718 to generate a phaseshifted oscillating signal 6720. Oscillating signal 6716 is also routedthrough a pulse shaper 6722, and phase shifted oscillating signal 6720is routed through a pulse shaper 6724. Pulse shaper 6722 and pulseshaper 6724 are both optional, and, when used, output a string of pulses6748 and a string of pulses 6750, respectively. String of pulses 6748 isconnected to the control input of switch 6726 and controls the frequencyat which switch 6726 closes and opens. String of pulses 6750 isconnected to the control input of switch 6728 and controls the frequencyat which switch 6728 closes and opens.

A signal 6734 from the first input of switch 6726 and a signal 6736 fromthe first input of switch 6728 are combined by a summer 6738. The outputof summer 6738 is a harmonically rich signal 6740 that is phasemodulated. Harmonically rich signal 6740 is comprised of a plurality ofharmonics and is routed to a filter 6742. Filter 6742 extracts one ormore of the harmonics as desired output signal 6744.

One exemplary implementation of the second modulation embodiment of thepresent invention is shown in FIG. 66 wherein a multiplication,modulation, and harmonic generation module 6600 generates a signal thatis phase and amplitude modulated, as described below. A firstinformation signal 6602 and a second information signal 6604 aremultiplied by a multiplier 6606. For ease of discussion, and not meantto be limiting, first information signal 6602 will be considered to be adigital signal, and second information signal 6604 will be considered tobe an analog signal. The output of multiplier 6606 is a combined signal6608. Combined signal 6608 is preferably a digital signal having a baudrate substantially the same as the baud rate of first information signal6602 and whose bits have amplitudes that are a function of the amplitudeof second information signal 6604.

Combined signal 6608 is routed through an optional filter 6610. Thisresults in a filtered combined signal 6612. Filtered combined signal6612 is connected through a load, shown as an inductor 6614, to thefirst input of a switch 6616. The second input of switch 6616 isconnected to a reference 6626. Preferably, reference 6626 is at thepotential about which first information signal 6602 switches. That is,if first information signal 6602 is a digital signal whose “low” valueis 0 volts and whose “high” value is 5 volts, then reference 6626 willbe between 0 and 5 volts, such as, for example, 2.5 volts. This exampleis for illustrative purposes only, and is not meant to be limiting. Aperson skilled in the relevant art(s) will understand that there are anumber of values for the “high,” “low,” and reference voltages whichwill result in a phase shift of the carrier when the “state” of theinformation signal crosses the reference voltage.

A local oscillator 6618 generates an oscillating signal 6620. Thefrequency of oscillating signal 6620 is a sub-harmonic of the desiredoutput frequency of the up-converter. Oscillating signal 6620 is routedthrough a pulse shaper 6622. Pulse shaper 6622 is optional, and, whenused, outputs a string of pulses 6624. String of pulses 6624 isconnected to the control input of switch 6616, and controls thefrequency at which switch 6616 closes and opens.

The first input of switch 6616 is also connected to the input of adifferentiation circuit 6628. In FIG. 66, differentiation circuit 6628is shown as being comprised of a capacitor 6630 in series and a resistor6632 shunted to ground. This circuit diagram is shown for illustrativepurposes only, and persons skilled in the art(s) will appreciate thatother differentiating circuits may be used. The output ofdifferentiation circuit 6628 is a harmonically rich signal 6634 that isboth phase and amplitude modulated. In summary, first information signal6602, the digital signal, phase modulates harmonically rich signal 6634,and second information signal 6604, the analog signal, amplitudemodulates harmonically rich signal 6634.

Harmonically rich signal 6634 is comprised of a plurality of harmonicsand is routed to a filter 6636. Filter 6636 extracts one or more of theharmonics as desired output signal 6638.

Although the discussion herein was directed toward a digital and ananalog signal, the invention is not limited to this implementation. Theoutput of differentiation circuit 6628 is such that the phase modulationis a function of an information signal whose high and low states areabove and below the reference voltage, and the amplitude modulation is afunction of the information signal whose voltage remains either above orbelow the reference voltage, but does not cross it.

A second exemplary implementation of the second modulation embodiment isshown in FIG. 68 wherein a multiplication, modulation, and harmonicgeneration module 6800 generates a signal that is phase and amplitudemodulated, as described below. A first information signal 6802 and asecond information signal 6804 are multiplied by a multiplier 6806. Forease of discussion, and not meant to be limiting, first informationsignal 6802 will be considered to be a digital signal, and secondinformation signal 6804 will be considered to be an analog signal. Theoutput of multiplier 6806 is a combined signal 6808. Combined signal6808 is a digital signal having a baud rate substantially the same asthe baud rate of first information signal 6802 and whose bits haveamplitudes that are a function of the amplitude of second informationsignal 6804.

Combined signal 6808 is routed through an optional filter 6810. Thisresults in a filtered combined signal 6812. Filtered combined signal6812 is connected to a buffer/inverter module 6814. Buffer/invertermodule 6814 outputs a buffered combined signal 6820 and an invertedcombined signal 6822. Buffered combined signal 6820 is substantially thesame as filtered combined signal 6812 and inverted combined signal 6822is substantially equal to the inverse of buffered combined signal 6820.A number of circuits, such as off-the-shelf buffers and off-the-shelfinverters, or custom designed buffers and inverters, can be used toaccomplish the function of buffer/inverter module 6814, as can beappreciated by those skilled in the relevant art(s).

Buffered combined signal 6820 is then routed through a load, shown as aninductor 6840, to the first input of a switch 6844, and invertedcombined signal 6822 is routed through a load, shown as an inductor6842, to the first input of a switch 6846. The second input of switch6844 and the second input of switch 6846 are connected to a reference6848. As shown in FIG. 68, the second input of switch 6844 and thesecond input of switch 6846 are connected to the same reference 6848.Those skilled in the relevant art(s) will understand that this does notneed to be the same reference. Typically, reference 6848 is at thepotential about which first information signal 6802 switches. That is,if first information signal 6802 is a digital signal whose “low” valueis 0 volts and whose “high” value is 5 volts, then reference 6848 willbe between 0 and 5 volts, such as, for example, 2.5 volts. This exampleis for illustrative purposes only, and is not meant to be limiting. Aperson skilled in the relevant art(s) will understand that there are anumber of values for the “high,” “low,” and reference voltages whichwill result in a phase shift of the carrier when the “state” of theinformation signal crosses the reference voltage.

A local oscillator 6824 generates an oscillating signal 6826. Thefrequency of oscillating signal 6826 is preferably an odd sub-harmonicof the desired output frequency of the up-converter. Oscillating signal6826 is routed through a 180° phase shifter 6828 to generate a phaseshifted oscillating signal 6830. Oscillating signal 6826 is also routedthrough a pulse shaper 6832, and phase shifted oscillating signal 6830is routed through a pulse shaper 6834. Pulse shaper 6832 and pulseshaper 6834 are both optional, and, when used, output a string of pulses6836 and a string of pulses 6838, respectively. String of pulses 6836 isconnected to the control input of switch 6844 and controls the frequencyat which switch 6844 closes and opens. String of pulses 6838 isconnected to the control input of switch 6846 and controls the frequencyat which switch 6846 closes and opens.

A signal 6850 from the first input of switch 6844 and a signal 6852 fromthe first input of switch 6846 are combined by a summer 6854. The outputof summer 6854 is a harmonically rich signal 6856 that is both phase andamplitude modulated. In summary, first information signal 6802, thedigital signal, phase modulates harmonically rich signal 6854, andsecond information signal 6804, the analog signal, amplitude modulatesharmonically rich signal 6856.

Harmonically rich signal 6856 is comprised of a plurality of harmonicsand is routed to a filter 6858. Filter 6858 extracts one or more of theharmonics as desired output signal 6860.

Although the discussion herein was directed toward a digital and ananalog signal, the invention is not limited to this implementation. Theoutput of the circuit is such that the phase modulation is a function ofan information signal whose high and low states are above and below thereference voltage, and the amplitude modulation is a function of theinformation signal whose voltage remains either above or below thereference voltage, but does not cross it. Thus the amplitude ispreserved.

One exemplary implementation of the third modulation embodiment is the“I/Q” embodiment shown in FIG. 69. A first information signal 6902 isrouted through an optional filter 6906. This results in a first filteredinformation signal 6910. Typically, first information signal 6902 (aswell as first filtered information signal 6910) is a digital signal,although the invention may be able to operate with analog signals. Firstfiltered information signal 6910 is connected through a load, shown asan inductor 6914, to the first input of a switch 6934. The second inputof switch 6934 is connected to a reference 6938. In one implementation,reference 6938 is at ground and, in another implementation, reference6938 is at a non-zero voltage.

A second information signal 6904 is routed through an optional filter6908. This results in a second filtered information signal 6912.Typically, second information signal 6904 (as well as second filteredinformation signal 6912) is a digital signal, although the invention mayoperate with analog signals. Second filtered information signal 6912 isconnected through a load, shown as an inductor 6916, to the first inputof a switch 6936. The second input of switch 6936 is connected to areference 6940. In one implementation, reference 6940 is at ground and,in another implementation, reference 6940 is at a non-zero voltage.

A local oscillator 6918 generates an in-phase, “I,” oscillating signal6920. The frequency of “I” oscillating signal 6920 is a sub-harmonic ofthe desired output frequency of the up-converter. “I” oscillating signal6920 is routed through a pulse shaper 6926. Pulse shaper 6926 isoptional, and, when used, outputs an “I” string of pulses 6930. “I”string of pulses 6930 is connected to the control input of switch 6934,and controls the frequency at which switch 6934 closes and opens.

“I” oscillating signal 6920 is also routed through a 90° phase shifter6922. The output of 90° phase shifter 6922 is a quadrature-phase, “Q,”oscillating signal 6924. “Q” oscillating signal 6924 is routed through apulse shaper 6928. Pulse shaper 6928 is optional, and, when used,outputs a “Q” string of pulses 6932. “Q” string of pulses 6932 isconnected to the control input of switch 6936, and controls thefrequency at which switch 6936 closes and opens.

The first input of switch 6934 is also connected to the input of adifferentiation circuit 6942. In FIG. 69, differentiation circuit 6942is shown as being comprised of a capacitor 6944 in series and a resistor6946 shunted to ground. This circuit diagram is shown for illustrativepurposes only, and persons skilled in the art(s) will appreciate thatother differentiating circuits may be used. The output ofdifferentiation circuit 6942 is a harmonically rich “I” signal 6954 thatis phase modulated.

The first input of switch 6936 is also connected to the input of adifferentiation circuit 6948. In FIG. 69, differentiation circuit 6948is shown as being comprised of a capacitor 6950 in series and a resistor6952 shunted to ground. This circuit diagram is shown for illustrativepurposes only, and persons skilled in the art(s) will appreciate thatother differentiating circuits may be used. The output ofdifferentiation circuit 6948 is a harmonically rich “Q” signal 6956 thatis phase modulated. Harmonically rich “I” signal 6954 and harmonicallyrich “Q” signal 6956 are then routed to a summer 6958 where they arecombined. Summer 6958 outputs harmonically rich “I/Q” signal 6960.Harmonically rich “I/Q” signal 6960 is comprised of a plurality ofharmonics and is routed to a filter 6962. Filter 6962 extracts one ormore of the harmonics as desired “I/Q” output signal 6964.

A second exemplary implementation of the third modulation embodiment isthe “I/Q” embodiment shown in FIG. 70. A first information signal 7002is routed to an optional filter 7006. This results in a first filteredinformation signal 7008. Typically, first information signal 7002 (aswell as first filtered information signal 7008) is a digital signal,although the invention may operate with analog signals. First filteredinformation signal 7008 is connected to a first buffer/inverter module7010. First buffer/inverter module 7010 outputs a buffered firstinformation signal 7016 and an inverted first information signal 7018.Buffered first information signal 7016 is substantially the same asfirst filtered information signal 7008 and inverted first informationsignal 7018 is substantially equal to the inverse of buffered firstinformation signal 7016. A number of circuits, such as off-the-shelfbuffers and off-the-shelf inverters, or custom designed buffers andinverters, can be used to accomplish the function of buffer/invertermodule 7010, as can be appreciated by those skilled in the relevantart(s).

Buffered first information signal 7016 is then routed through a load,shown as an inductor 7066, to the first input of a switch 7074, andinverted first information signal 7018 is routed through a load, shownas an inductor 7068, to the first input of a switch 7076. The secondinput of switch 7074 and the second input of switch 7076 are connectedto a reference 7082. As shown in FIG. 70, the second input of switch7074 and the second input of switch 7076 are connected to the samereference 7082. Those skilled in the relevant art(s) will understandthat this does not need to be the same reference. In one implementation,reference 7082 is at ground and in another implementation reference 7082is at a non-zero voltage.

A second information signal 7004 is routed to an optional filter 7036.This results in a second filtered information signal 7038. Typically,second information signal 7004 (as well as second filtered informationsignal 7038) is a digital signal. Second filtered information signal7038 is connected to a second buffer/inverter module 7040. Secondbuffer/inverter module 7040 outputs a buffered second information signal7046 and an inverted second information signal 7048. Buffered secondinformation signal 7046 is substantially the same as second filteredinformation signal 7038 and inverted second information signal 7048 issubstantially equal to the inverse of buffered second information signal7046. A number of circuits, such as off-the-shelf buffers andoff-the-shelf inverters, or custom designed buffers and inverters, canbe used to accomplish the function of buffer/inverter module 7040, ascan be appreciated by those skilled in the relevant art(s).

Buffered second information signal 7046 is then routed through a load,shown as an inductor 7070, to the first input of a switch 7078, andinverted second information signal 7048 is routed through a load, shownas an inductor 7072, to the first input of a switch 7080. The secondinput of switch 7078 and the second input of switch 7080 are connectedto a reference 7084. As shown in FIG. 70, the second input of switch7078 and the second input of switch 7080 are connected to the samereference 7084. Those skilled in the relevant art(s) will understandthat this does not need to be the same reference. In one implementation,reference 7084 is at ground and in another implementation reference 7084is at a non-zero voltage.

A local oscillator 7020 generates an in-phase, “I,” oscillating signal7022. The frequency of “I” oscillating signal 7022 is preferably an oddsub-harmonic of the desired output frequency of the up-converter. “I”oscillating signal 7022 is routed through a 180° phase shifter 7024 togenerate a 180° phase shifted “I” oscillating signal 7026. “I”oscillating signal 7022 is also routed through a pulse shaper 7028, and180° phase shifted “I” oscillating signal 7026 is routed through a pulseshaper 7030. Pulse shaper 7028 and pulse shaper 7030 are both optional,and, when used, output an “I” string of pulses 7032 and an “I” string ofpulses 7034, respectively. “I” string of pulses 7032 is connected to thecontrol input of switch 7074 and controls the frequency at which switch7074 closes and opens. “I” string of pulses 7034 is connected to thecontrol input of switch 7076 and controls the frequency at which switch7076 closes and opens.

An “I” signal 7086 from the first input of switch 7074 and an “I” signal7088 from the first input of switch 7076 are combined by a summer 7094.The output of summer 7094 is a harmonically rich “I” signal 7081 that isphase modulated.

“I” oscillating signal 7022 is also routed through a 90° phase shifter7050 to generate a quadrature-phase, “Q,” oscillating signal 7052. “Q”oscillating signal 7052 is routed through a 180° phase shifter 7054 togenerate a 180° phase shifted “Q” oscillating signal 7056. “Q”oscillating signal 7052 is also routed through a pulse shaper 7058, and180° phase shifted “Q” oscillating signal 7056 is routed through a pulseshaper 7060. Pulse shaper 7058 and pulse shaper 7060 are both optional,and, when used, output a “Q” string of pulses 7062 and a “Q” string ofpulses 7064, respectively. “Q” string of pulses 7062 is connected to thecontrol input of switch 7078 and controls the frequency at which switch7078 closes and opens. “Q” string of pulses 7064 is connected to thecontrol input of switch 7080 and controls the frequency at which switch7080 closes and opens.

A “Q” signal 7090 from the first input of switch 7078 and a “Q” signal7092 from the first input of switch 7080 are combined by a summer 7096.The output of summer 7096 is a harmonically rich “Q” signal 7083 that isphase modulated.

Harmonically rich “I” signal 7081 and harmonically rich “Q” signal 7083are combined by summer 7085 which outputs a harmonically rich “I/Q”signal 7087. Harmonically rich “I/Q” signal 7087 is comprised of aplurality of harmonics and is routed to a filter 7089. Filter 7089extracts one or more of the harmonics as desired “I/Q” output signal7098.

In the fourth modulation embodiment, four information signals aremodulated onto an “I/Q” carrier as shown in the example of FIG. 71. Afirst information signal 7102 and a second information signal 7104 arereceived by a multiplication, modulation, and harmonic generation module7110. A first exemplary implementation of multiplication, modulation,and harmonic generation module 7110 is shown in FIG. 66 asmultiplication, modulation, and harmonic generation module 6600 and asecond exemplary implementation of multiplication, modulation, andharmonic generation module 7110 is shown in FIG. 68 as multiplication,modulation, and harmonic generation module 6800. Based on the teachingscontained herein, other implementations will be apparent to personsskilled in the relevant art(s).

A local oscillator 7114 generates an in-phase, “I,” oscillating signal7116. The frequency of “I” oscillating signal 7116 is a sub-harmonicfrequency of the desired output frequency of the up-converter, and isreceived by multiplication, modulation, and harmonic generation module7110, and causes it to output a harmonically rich “I” signal 7122 thatis both phase and amplitude modulated. In the exemplary implementationwherein the multiplication, modulation, and harmonic generation module7110 is multiplication, modulation, and harmonic generation module 6800,the frequency of “I” oscillating signal 7116 is an odd sub-harmonic ofthe desired output frequency.

A third information signal 7106 and a fourth information signal 7108 arereceived by a multiplication, modulation, and harmonic generation module7112. A first exemplary implementation of multiplication, modulation,and harmonic generation module 7112 is shown in FIG. 66 asmultiplication, modulation, and harmonic generation module 6600 and asecond exemplary implementation of multiplication, modulation, andharmonic generation module 7112 is shown in FIG. 68 as multiplication,modulation, and harmonic generation module 6800. Based on the teachingscontained herein, other implementations will be apparent to personsskilled in the relevant art(s).

“I” oscillating signal 7116 is routed to 90° phase shifter 7118. Theoutput of 90° phase shifter 7118 is a quadrature-phase, “Q,” oscillatingsignal 7120. “Q” oscillating signal 7120 is received by multiplication,modulation, and harmonic generation module 7112 and causes it to outputa harmonically rich “Q” signal 7124 that is both phase and amplitudemodulated.

Harmonically rich “I” signal 7122 and harmonically rich “Q” signal 7124are combined by a summer 7126. The output of summer 7126 is aharmonically rich “I/Q” signal 7128. Harmonically rich “I/Q” signal 7128is comprised of a plurality of harmonics and is routed to a filter 7130.Filter 7130 extracts one or more of the harmonics as desired “I/Q”output signal 7132. Desired “I/Q” output signal 7132 is phase andamplitude modulated on the “I” phase and phase and amplitude modulatedon the “Q” phase, as discussed above in the discussion of the secondmodulation embodiment.

3.3 Methods and Systems for Implementing the Embodiments.

Exemplary operational and/or structural implementations related to themethod(s), structure(s), and/or embodiments described above arepresented in this section (and its subsections). These components andmethods are presented herein for purposes of illustration, and notlimitation. The invention is not limited to the particular examples ofcomponents and methods described herein. Alternatives (includingequivalents, extensions, variations, deviations, etc., of thosedescribed herein) will be apparent to persons skilled in the relevantart(s) based on the teachings contained herein. Such alternatives fallwithin the scope and spirit of the present invention.

3.3.1 The Voltage Controlled Oscillator (FM Mode).

As discussed above, the frequency modulation (FM) mode embodiment of theinvention uses a voltage controlled oscillator (VCO). See, as anexample, VCO 1204 in FIG. 12. The invention supports numerousembodiments of the VCO. Exemplary embodiments of the VCO 2304 (FIG. 23)are described below. However, it should be understood that theseexamples are provided for illustrative purposes only. The invention isnot limited to these embodiments.

3.3.1.1 Operational Description.

The information signal 2302 is accepted and an oscillating signal 2306whose frequency varies as a function of the information signal 2302 iscreated. Oscillating signal 2306 is also referred to as frequencymodulated intermediate signal 2306. The information signal 2302 may beanalog or digital or a combination thereof, and may be conditioned toensure it is within the desired range.

In the case where the information signal 2302 is digital, theoscillating signal 2306 may vary between discrete frequencies. Forexample, in a binary system, a first frequency corresponds to a digital“high,” and a second frequency corresponds to a digital “low.” Eitherfrequency may correspond to the “high” or the “low,” depending on theconvention being used. This operation is referred to as frequency shiftkeying (FSK) which is a subset of FM. If the information signal 2302 isanalog, the frequency of the oscillating signal 2306 will vary as afunction of that analog signal, and is not limited to the subset of FSKdescribed above.

The oscillating signal 2306 is a frequency modulated signal which can bea sinusoidal wave, a rectangular wave, a triangular wave, a pulse, orany other continuous and periodic waveform. As stated above, one skilledin the relevant art(s) will recognize the physical limitations to andmathematical obstacles against achieving exact or perfect waveforms andit is not the intent of the present invention that a perfect waveform begenerated or needed. Again, as stated above, for ease of discussion, theterm “rectangular waveform” will be used to refer to waveforms that aresubstantially rectangular, the term “square wave” will refer to thosewaveforms that are substantially square, the term “triangular wave” willrefer to those waveforms that are substantially triangular, and the term“pulse” will refer to those waveforms that are substantially a pulse,and it is not the intent of the present invention that a perfect squarewave, triangle wave, or pulse be generated or needed.

3.3.1.2 Structural Description.

The design and use of a voltage controlled oscillator 2304 is well knownto those skilled in the relevant art(s). The VCO 2304 may be designedand fabricated from discrete components, or it may be purchased “off theshelf.” VCO 2304 accepts an information signal 2302 from a source. Theinformation signal 2302 is at baseband and generally is an electricalsignal within a prescribed voltage range. If the information is digital,the voltage will be at discrete levels. If the information is analog,the voltage will be continuously variable between an upper and a lowerlevel. The VCO 2304 uses the voltage of the information signal 2302 tocause a modulated oscillating signal 2306 to be output. The informationsignal 2302, because it is a baseband signal and is used to modulate theoscillating signal, may be referred to as the modulating baseband signal2302.

The frequency of the oscillating signal 2306 varies as a function of thevoltage of the modulating baseband signal 2302. If the modulatingbaseband signal 2302 represents digital information, the frequency ofthe oscillating signal 2306 will be at discrete levels. If, on the otherhand, the modulating baseband signal 2302 represents analog information,the frequency of the oscillating signal 2306 will be continuouslyvariable between its higher and lower frequency limits. The oscillatingsignal 2306 can be a sinusoidal wave, a rectangular wave, a triangularwave, a pulse, or any other continuous and periodic waveform.

The frequency modulated oscillating signal 2306 may then be used todrive a switch module 2802.

3.3.2 The Local Oscillator (PM, AM, and “I/Q” Modes).

As discussed above, the phase modulation (PM) and amplitude modulation(AM) mode embodiments of the invention use a local oscillator. So toodoes the in-phase/quadrature-phase modulation (“I/Q”) mode embodiment.See, as an example, local oscillator 1406 in FIG. 14, local oscillator1610 in FIG. 16, and local oscillator 1806 in FIG. 18. The inventionsupports numerous embodiments of the local oscillator. Exemplaryembodiments of the local oscillator 2402 (FIG. 24) are described below.However, it should be understood that these examples are provided forillustrative purposes only. The invention is not limited to theseembodiments.

3.3.2.1 Operational Description.

An oscillating signal 2404 is generated. The frequency of the signal2404 may be selectable, but generally is not considered to be“variable.” That is, the frequency may be selected to be a specificvalue for a specific implementation, but generally it does not vary as afunction of the information signal 2302 (i.e., the modulating basebandsignal).

The oscillating signal 2404 generally is a sinusoidal wave, but it mayalso be a rectangular wave, a triangular wave, a pulse, or any othercontinuous and periodic waveform. As stated above, one skilled in therelevant art(s) will recognize the physical limitations to andmathematical obstacles against achieving exact or perfect waveforms andit is not the intent of the present invention that a perfect waveform begenerated or needed. Again, as stated above, for ease of discussion, theterm “rectangular waveform” will be used to refer to waveforms that aresubstantially rectangular, the term “square wave” will refer to thosewaveforms that are substantially square, the term “triangular wave” willrefer to those waveforms that are substantially triangular, and the term“pulse” will refer to those waveforms that are substantially a pulse,and it is not the intent of the present invention that a perfect squarewave, triangle wave, or pulse be generated or needed.

3.3.2.2 Structural Description.

The design and use of a local oscillator 2402 is well known to thoseskilled in the relevant art(s). A local oscillator 2402 may be designedand fabricated from discrete components or it may be purchased “off theshelf.” A local oscillator 2402 is generally set to output a specificfrequency. The output can be “fixed” or it can be “selectable,” based onthe design of the circuit. If it is fixed, the output is considered tobe substantially a fixed frequency that cannot be changed. If the outputfrequency is selectable, the design of the circuit will allow a controlsignal to be applied to the local oscillator 2402 to change thefrequency for different applications. However, the output frequency of alocal oscillator 2402 is not considered to be “variable” as a functionof an information signal 2302 such as the modulating baseband signal2302. (If it were desired for the output frequency of an oscillator tobe variable as a function of an information signal, a VCO wouldpreferably be used.) The oscillating signal 2404 generally is asinusoidal wave, but it may also be a rectangular wave, a triangularwave, a pulse, or any other continuous and periodic waveform.

The output of a local oscillator 2402 may be an input to other circuitcomponents such as a phase modulator 2606, a phase shifting circuit2504, switch module 3102, etc.

3.3.3 The Phase Shifter (“I/Q”Mode).

As discussed above, the in-phase/quadrature-phase modulation (“I/Q”)mode embodiment of the invention uses a phase shifter. See, as anexample, phase shifter 1810 in FIG. 18. The invention supports numerousembodiments of the phase shifter. Exemplary embodiments of the phaseshifter 2504 (FIG. 25) are described below. The invention is not limitedto these embodiments. The description contained herein is for a “90°phase shifter.” The 90° phase shifter is used for ease of explanation,and one skilled in the relevant art(s) will understand that other phaseshifts can be used without departing from the intent of the presentinvention.

3.3.3.1 Operational Description.

An “in-phase” oscillating signal 2502 is received and a“quadrature-phase” oscillating signal 2506 is output. If the in-phase(“I”) signal 2502 is referred to as being a sine wave, then thequadrature-phase (“Q”) signal 2506 can be referred to as being a cosinewave (i.e., the “Q” signal 2506 is 90° out of phase with the “I” signal2502). However, they may also be rectangular waves, triangular waves,pulses, or any other continuous and periodic waveforms. As stated above,one skilled in the relevant art(s) will recognize the physicallimitations to and mathematical obstacles against achieving exact orperfect waveforms and it is not the intent of the present invention thata perfect waveform be generated or needed. Again, as stated above, forease of discussion, the term “rectangular waveform” will be used torefer to waveforms that are substantially rectangular, the term “squarewave” will refer to those waveforms that are substantially square, theterm “triangular wave” will refer to those waveforms that aresubstantially triangular, and the term “pulse” will refer to thosewaveforms that are substantially a pulse, and it is not the intent ofthe present invention that a perfect square wave, triangle wave, orpulse be generated or needed. Regardless of the shapes of the waveforms,the “Q” signal 2506 is out of phase with the “I” signal 2506 byone-quarter period of the waveform. The frequency of the “I” and “Q”signals 2502 and 2506 are substantially equal.

The discussion contained herein will be confined to the more prevalentembodiment wherein there are two intermediate signals separated by 90°.This is not limiting on the invention. It will be apparent to thoseskilled in the relevant art(s) that the techniques tough herein andapplied to the “I/Q” embodiment of the present invention also apply tomore exotic embodiments wherein the intermediate signals are shifted bysome amount other than 90°, and also wherein there may be more than twointermediate frequencies.

3.3.3.2 Structural Description.

The design and use of a phase shifter 2504 is well known to thoseskilled in the relevant art(s). A phase shifter 2504 may be designed andfabricated from discrete components or it may be purchased “off theshelf.” A phase shifter accepts an “in-phase” (“I”) oscillating signal2502 from any of a number of sources, such as a VCO 2304 or a localoscillator 2402, and outputs a “quadrature-phase” (“Q”) oscillatingsignal 2506 that is substantially the same frequency and substantiallythe same shape as the incoming “I” signal 2502, but with the phaseshifted by 90°. Both the “I” and “Q” signals 2502 and 2506 are generallysinusoidal waves, but they may also be rectangular waves, triangularwaves, pulses, or any other continuous and periodic waveforms.Regardless of the shapes of the waveforms, the “Q” signal 2506 is out ofphase with the “I” signal 2502 by one-quarter period of the waveform.Both the “I” and “Q” signals 2502 and 2506 may be modulated.

The output of a phase shifter 2504 may be used as an input to a phasemodulator 2606.

3.3.4 The Phase Modulator (PM and “I/Q” Modes).

As discussed above, the phase modulation (PM) mode embodiment includingthe in-phase/quadrature-phase modulation (“I/Q”) mode embodiment of theinvention uses a phase modulator. See, as an example, phase modulator1404 of FIG. 14 and phase modulators 1804 and 1816 of FIG. 18. Theinvention supports numerous embodiments of the phase modulator.Exemplary embodiments of the phase modulator 2606 (FIG. 26) aredescribed below. However, it should be understood that these examplesare provided for illustrative purposes only. The invention is notlimited to these embodiments.

3.3.4.1 Operational Description.

An information signal 2602 and an oscillating signal 2604 are accepted,and a phase modulated oscillating signal 2608 whose phase varies as afunction of the information signal 2602 is output. The informationsignal 2602 may be analog or digital and may be conditioned to ensure itis within the desired range. The oscillating signal 2604 can be asinusoidal wave, a rectangular wave, a triangular wave, a pulse, or anyother continuous and periodic waveform. As stated above, one skilled inthe relevant art(s) will recognize the physical limitations to andmathematical obstacles against achieving exact or perfect waveforms andit is not the intent of the present invention that a perfect waveform begenerated or needed. Again, as stated above, for ease of discussion, theterm “rectangular waveform” will be used to refer to waveforms that aresubstantially rectangular, the term “square wave” will refer to thosewaveforms that are substantially square, the term “triangular wave” willrefer to those waveforms that are substantially triangular, and the term“pulse” will refer to those waveforms that are substantially a pulse,and it is not the intent of the present invention that a perfect squarewave, triangle wave, or pulse be generated or needed. The modulatedoscillating signal 2608 is also referred to as the modulatedintermediate signal 2608.

In the case where the information signal 2602 is digital, the modulatedintermediate signal 2608 will shift phase between discrete values, thefirst phase (e.g., for a signal represented by sin (ωt+θ_(o)))corresponding to a digital “high,” and the second phase (e.g., for asignal represented by sin (ωt+θ_(o)+δ), where δ represents the amountthe phase has been shifted) corresponding to a digital “low.” Eitherphase may correspond to the “high” or the “low,” depending on theconvention being used. This operation is referred to as phase shiftkeying (PSK) which is a subset of PM.

If the information signal 2602 is analog, the phase of the modulatedintermediate signal 2608 will vary as a function of the informationsignal 2602 and is not limited to the subset of PSK described above.

The modulated intermediate signal 2608 is a phase modulated signal whichcan be a sinusoidal wave, a rectangular wave, a triangular wave, apulse, or any other continuous and periodic waveform, and which hassubstantially the same period as the oscillating signal 2604.

3.3.4.2 Structural Description.

The design and use of a phase modulator 2606 is well known to thoseskilled in the relevant art(s). A phase modulator 2606 may be designedand fabricated from discrete components, or it may be purchased “off theshelf.” A phase modulator 2606 accepts an information signal 2602 from asource and an oscillating signal 2604 from a local oscillator 2402 or aphase shifter 2504. The information signal 2602 is at baseband and isgenerally an electrical signal within a prescribed voltage range. If theinformation is digital, the voltage will be at discrete levels. If theinformation is analog, the voltage will be continuously variable betweenan upper and a lower level as a function of the information signal 2602.The phase modulator 2606 uses the voltage of the information signal 2602to modulate the oscillating signal 2604 and causes a modulatedintermediate signal 2608 to be output. The information signal 2602,because it is a baseband signal and is used to modulate the oscillatingsignal, may be referred to as the modulating baseband signal 2604.

The modulated intermediate signal 2608 is an oscillating signal whosephase varies as a function of the voltage of the modulating basebandsignal 2602. If the modulating baseband signal 2602 represents digitalinformation, the phase of the modulated intermediate signal 2608 willshift by a discrete amount (e.g., the modulated intermediate signal 2608will shift by an amount δ between sin (ωt+θ_(o)) and sin (ωt+θ_(o)+δ)).If, on the other hand, the modulating baseband signal 2602 representsanalog information, the phase of the modulated intermediate signal 2608will continuously shift between its higher and lower phase limits as afunction of the information signal 2602. In one exemplary embodiment,the upper and lower limits of the modulated intermediate signal 2608 canbe represented as sin(ωt+θ_(o)) and sin(ωt+θ_(o)+π). In otherembodiments, the range of the phase shift may be less than π. Themodulated intermediate signal 2608 can be a sinusoidal wave, arectangular wave, a triangular wave, a pulse, or any other continuousand periodic waveform.

The phase modulated intermediate signal 2608 may then be used to drive aswitch module 2802.

3.3.5 The Summing Module (AM Mode).

As discussed above, the amplitude modulation (AM) mode embodiment of theinvention uses a summing module. See, as an example, summing module 1606in FIG. 16. The invention supports numerous embodiments of the summingmodule. Exemplary embodiments of the summing module 2706 (FIG. 27) aredescribed below. However, it should be understood that these examplesare provided for illustrative purposes only. The invention is notlimited to these embodiments. It may also be used in the “I/Q” modeembodiment when the modulation is AM. The summing module 2706 need notbe used in all AM embodiments.

3.3.5.1 Operational Description.

An information signal 2702 and a bias signal 2702 are accepted, and areference signal is output. The information signal 2702 may be analog ordigital and may be conditioned to ensure it is within the proper rangeso as not to damage any of the circuit components. The bias signal 2704is usually a direct current (DC) signal.

In the case where the information signal 2702 is digital, the referencesignal 2706 shifts between discrete values, the first valuecorresponding to a digital “high,” and the second value corresponding toa digital “low.” Either value may correspond to the “high” or the “low,”depending on the convention being used. This operation is referred to asamplitude shift keying (ASK) which is a subset of AM.

If the information signal 2702 is analog, the value of the referencesignal 2708 will vary linearly between upper and lower extremes whichcorrespond to the upper and lower limits of the information signal 2702.Again, either extreme of the reference signal 2708 range may correspondto the upper or lower limit of the information signal 2702 depending onthe convention being used.

The reference signal 2708 is a digital or analog signal and issubstantially proportional to the information signal 2702.

3.3.5.2 Structural Description.

The design and use of a summing module 2706 is well known to thoseskilled in the relevant art(s). A summing module 2706 may be designedand fabricated from discrete components, or it may be purchased “off theshelf” A summing module 2706 accepts an information signal 2702 from asource. The information signal 2702 is at baseband and generally is anelectrical signal within a prescribed voltage range. If the informationis digital, the information signal 2702 is at either of two discretelevels. If the information is analog, the information signal 2702 iscontinuously variable between an upper and a lower level. The summingmodule 2706 uses the voltage of the information signal 2702 and combinesit with a bias signal 2704. The output of the summing module 2706 iscalled the reference signal 2708. The purpose of the summing module 2706is to cause the reference signal 2708 to be within a desired signalrange. One skilled in the relevant art(s) will recognize that theinformation signal 2702 may be used directly, without being summed witha bias signal 2704, if it is already within the desired range. Theinformation signal 2702 is a baseband signal, but typically, in an AMembodiment, it is not used to directly modulate an oscillating signal.The amplitude of the reference signal 2708 is at discrete levels if theinformation signal 2702 represents digital information. On the otherhand, the amplitude of the reference signal 2708 is continuouslyvariable between its higher and lower limits if the information signal2702 represents analog information. The amplitude of the referencesignal 2708 is substantially proportional to the information signal2702, however, a positive reference signal 2708 need not represent apositive information signal 2702.

The reference signal 2708 is routed to the first input 3108 of a switchmodule 3102. In one exemplary embodiment, a resistor 2824 is connectedbetween the output of the summing module 2706 (or the source of theinformation signal 2702 in the embodiment wherein the summing amplifier2706 is not used) and the switch 3116 of the switch module 3102.

3.3.6 The Switch Module (FM, PM, and “I/Q” Modes).

As discussed above, the frequency modulation (FM), phase modulation(PM), and the in-phase/quadrature-phase modulation (“I/Q”) modeembodiments of the invention use a switching assembly referred to asswitch module 2802 (FIGS. 28A-28C). As an example, switch module 2802 isa component in switch module 1214 in FIG. 12, switch module 1410 in FIG.14, and switch modules 1822 and 1828 in FIG. 18. The invention supportsnumerous embodiments of the switch module. Exemplary embodiments of theswitch module 2802 are described below. However, it should be understoodthat these examples are provided for illustrative purposes only. Theinvention is not limited to these embodiments. The switch module 2802and its operation in the FM, PM, and “I/Q” mode embodiments issubstantially the same as its operation in the AM mode embodiment,described in sections 3.3.7-3.3.7.2 below.

3.3.6.1 Operational Description.

A bias signal 2806 is gated as a result of the application of amodulated oscillating signal 2804, and a signal with a harmonically richwaveform 2814 is created. The bias signal 2806 is generally a fixedvoltage. The modulated oscillating signal 2804 can be frequencymodulated, phase modulated, or any other modulation scheme orcombination thereof. In certain embodiments, such as in certainamplitude shift keying modes, the modulated oscillating signal 2804 mayalso be amplitude modulated. The modulated oscillating signal 2804 canbe a sinusoidal wave, a rectangular wave, a triangular wave, a pulse, orany other continuous and periodic waveform. In a preferred embodiment,modulated oscillating signal 2804 would be a rectangular wave. As statedabove, one skilled in the relevant art(s) will recognize the physicallimitations to and mathematical obstacles against achieving exact orperfect waveforms and it is not the intent of the present invention thata perfect waveform be generated or needed. Again, as stated above, forease of discussion, the term “rectangular waveform” will be used torefer to waveforms that are substantially rectangular, the term “squarewave” will refer to those waveforms that are substantially square, theterm “triangular wave” will refer to those waveforms that aresubstantially triangular, and the term “pulse” will refer to thosewaveforms that are substantially a pulse, and it is not the intent ofthe present invention that a perfect square wave, triangle wave, orpulse be generated or needed.

The signal with harmonically rich waveform 2814, hereafter referred toas the harmonically rich signal 2814, is a continuous and periodicwaveform that is modulated substantially the same as the modulatedoscillating signal 2804. That is, if the modulated oscillating signal2804 is frequency modulated, the harmonically rich signal 2814 will alsobe frequency modulated, and if the modulated oscillating signal 2804 isphase modulated, the harmonically rich signal 2814 will also be phasemodulated. (In one embodiment, the harmonically rich signal 2814 is asubstantially rectangular waveform.) As stated before, a continuous andperiodic waveform, such as a rectangular wave, has sinusoidal components(harmonics) at frequencies that are integer multiples of the fundamentalfrequency of the underlying waveform (the Fourier componentfrequencies). Thus, the harmonically rich signal 2814 is composed ofsinusoidal signals at frequencies that are integer multiples of thefundamental frequency of itself.

3.3.6.2 Structural Description.

The switch module 2802 of an embodiment of the present invention iscomprised of a first input 2808, a second input 2810, a control input2820, an output 2822, and a switch 2816. A bias signal 2806 is appliedto the first input 2808 of the switch module 2802. Generally, the biassignal 2806 is a fixed voltage, and in one embodiment of the invention,a resistor 2824 is located between the bias signal 2806 and the switch2816. The second input 2810 of the switch module 2802 is generally atelectrical ground 2812. However, one skilled in the relevant art(s) willrecognize that alternative embodiments exist wherein the second input2810 may not be at electrical ground 2812, but rather a second signal2818, provided that the second signal 2818 is different than the biassignal 2806.

A modulated oscillating signal 2804 is connected to the control input2820 of the switch module 2802. The modulated oscillating signal 2804may be frequency modulated or phase modulated. (In some circumstancesand embodiments, it may be amplitude modulated, such as in on/offkeying, but this is not the general case, and will not be describedherein.) The modulated oscillating signal 2804 can be a sinusoidal wave,a rectangular wave, a triangular wave, a pulse, or any other continuousand periodic waveform. In a preferred embodiment, it would be arectangular wave. The modulated oscillating signal 2804 causes theswitch 2816 to close and open.

The harmonically rich signal 2814 described in section 3.3.6.1 above, isfound at the output 2822 of the switch module 2802. The harmonicallyrich signal 2814 is a continuous and periodic waveform that is modulatedsubstantially the same as the modulated oscillating signal 2804. Thatis, if the modulated oscillating signal 2804 is frequency modulated, theharmonically rich signal 2814 will also be frequency modulated, and ifthe modulated oscillating signal 2804 is phase modulated, theharmonically rich signal 2814 will also be phase modulated. In oneembodiment, the harmonically rich signal 2814 has a substantiallyrectangular waveform. As stated before, a continuous and periodicwaveform, such as a rectangular wave, has sinusoidal components(harmonics) at frequencies that are integer multiples of the fundamentalfrequency of the underlying waveform (the Fourier componentfrequencies). Thus, the harmonically rich signal 2814 is composed ofsinusoidal signals at frequencies that are integer multiples of thefundamental frequency of itself. Each of these sinusoidal signals isalso modulated substantially the same as the continuous and periodicwaveform (i.e., the modulated oscillating signal 2804) from which it isderived.

The switch module 2802 operates as follows. When the switch 2816 is“open,” the output 2822 of switch module 2802 is at substantially thesame voltage level as bias signal 2806. Thus, since the harmonicallyrich signal 2814 is connected directly to the output 2822 of switchmodule 2802, the amplitude of harmonically rich signal 2814 is equal tothe amplitude of the bias signal 2806. When the modulated oscillatingsignal 2804 causes the switch 2816 to become “closed,” the output 2822of switch module 2802 becomes connected electrically to the second input2810 of switch module 2802 (e.g., ground 2812 in one embodiment of theinvention), and the amplitude of the harmonically rich signal 2814becomes equal to the potential present at the second input 2810 (e.g.,zero volts for the embodiment wherein the second input 2810 isconnected- to electrical ground 2812). When the modulated oscillatingsignal 2804 causes the switch 2816 to again become “open,” the amplitudeof the harmonically rich signal 2814 again becomes equal to the biassignal 2806. Thus, the amplitude of the harmonically rich signal 2814 isat either of two signal levels, i.e., bias signal 2806 or ground 2812,and has a frequency that is substantially equal to the frequency of themodulated oscillating signal 2804 that causes the switch 2816 to openand close. The harmonically rich signal 2814 is modulated substantiallythe same as the modulated oscillating signal 2804. One skilled in therelevant art(s) will recognize that any one of a number of switchdesigns will fulfill the scope and spirit of the present invention asdescribed herein.

In an embodiment of the invention, the switch 2816 is a semiconductordevice, such as a diode ring. In another embodiment, the switch is atransistor, such as a field effect transistor (FET). In an embodimentwherein the FET is gallium arsenide (GaAs), switch module 2802 can bedesigned as seen in FIGS. 29A-29C, where the modulated oscillatingsignal 2804 is connected to the gate 2902 of the GaAsFET 2901, the biassignal 2806 is connected through a bias resistor 2824 to the source 2904of the GaAsFET 2901, and electrical ground 2812 is connected to thedrain 2906 of GaAsFET 2901. (In an alternate embodiment shown in FIG.29C, a second signal 2818 may be connected to the drain 2906 of GaAsFET2901.) Since the drain and the source of GaAsFETs are interchangeable,the bias signal 2806 can be applied to either the source 2904 or to thedrain 2906. If there is concern that there might be some source-drainasymmetry in the GaAsFET, the switch module can be designed as shown inFIGS. 30A-30C, wherein two GaAsFETs 3002 and 3004 are connectedtogether, with the source 3010 of the first 3002 connected to the drain3012 of the second 3004, and the drain 3006 of the first 3002 beingconnected to the source 3008 of the second 3004. This design arrangementwill balance substantially all asymmetries.

An alternate implementation of the design includes a “dwell capacitor”wherein one side of a capacitor is connected to the first input of theswitch and the other side of the capacitor is connected to the secondinput of the switch. The purpose of the design is to increase theapparent aperture of the pulse without actually increasing its width.For additional detail on the design and use of a dwell capacitor, seeco-pending application entitled “Method and System for Down-ConvertingElectromagnetic Signals Having Optimized Switch Structures,” Ser. No.09/293,095, filed Apr. 16, 1999, and other applications as referencedabove.

Other switch designs and implementations will be apparent to personsskilled in the relevant art(s).

The output 2822 of the switch module 2802, i.e., the harmonically richsignal 2814, can be routed to a filter 3504 in the FM and PM modes or toa Summer 3402 in the “I/Q” mode.

3.3.7 The Switch Module (AM Mode).

As discussed above, the amplitude modulation (AM) mode embodiment of theinvention uses a switching assembly referred to as switch module 3102(FIGS. 31A-31C). As an example, switch module 3102 is a component inswitch module 1614 of FIG. 16. The invention supports numerousembodiments of the switch module. Exemplary embodiments of the switchmodule 3102 are described below. However, it should be understood thatthese examples are provided for illustrative purposes only. Theinvention is not limited to these embodiments. The switch module 3102and its operation in the AM mode embodiment is substantially the same asits operation in the FM, PM, and “I/Q” mode embodiments described insections 3.3.6-3.3.6.2. above.

3.3.7.1 Operational Description.

A reference signal 3106 is gated as a result of the application of anoscillating signal 3104, and a signal with a harmonically rich waveform3114 is created. The reference signal 3106 is a function of theinformation signal 2702 and may, for example, be either the summation ofthe information signal 2702 with a bias signal 2704 or it may be theinformation signal 2702 by itself. In the AM mode, the oscillatingsignal 3104 is generally not modulated, but can be.

The oscillating signal 3104 can be a sinusoidal wave, a rectangularwave, a triangular wave, a pulse, or any other continuous and periodicwaveform. In a preferred embodiment, it would be a rectangular wave. Asstated above, one skilled in the relevant art(s) will recognize thephysical limitations to and mathematical obstacles against achievingexact or perfect waveforms and it is not the intent of the presentinvention that a perfect waveform be generated or needed. Again, asstated above, for ease of discussion, the term “rectangular waveform”will be used to refer to waveforms that are substantially rectangular,the term “square wave” will refer to those waveforms that aresubstantially square, the term “triangular wave” will refer to thosewaveforms that are substantially triangular, and the term “pulse” willrefer to those waveforms that are substantially a pulse, and it is notthe intent of the present invention that a perfect square wave, trianglewave, or pulse be generated or needed.

The signal with a harmonically rich waveform 3114, hereafter referred toas the harmonically rich signal 3114, is a continuous and periodicwaveform whose amplitude is a function of the reference signal. That is,it is an AM signal. In one embodiment, the harmonically rich signal 3114has a substantially rectangular waveform. As stated before, a continuousand periodic waveform, such as a rectangular wave, will have sinusoidalcomponents (harmonics) at frequencies that are integer multiples of thefundamental frequency of the underlying waveform (the Fourier componentfrequencies). Thus, harmonically rich signal 3114 is composed ofsinusoidal signals at frequencies that are integer multiples of thefundamental frequency of itself.

Those skilled in the relevant art(s) will recognize that alternativeembodiments exist wherein combinations of modulations (e.g., PM and ASK,FM and AM, etc.) may be employed simultaneously. In these alternateembodiments, the oscillating signal 3104 may be modulated. Thesealternate embodiments will be apparent to persons skilled in therelevant art(s), and thus will not be described herein.

3.3.7.2 Structural Description.

The switch module 3102 of the present invention is comprised of a firstinput 3108, a second input 3110, a control input 3120, an output 3122,and a switch 3116. A reference signal 3106 is applied to the first input3108 of the switch module 3102. Generally, the reference signal 3106 isa function of the information signal 2702, and may either be thesummation of the information signal 2702 with a bias signal or it may bethe information signal 2702 by itself. In one embodiment of theinvention, a resistor 3124 is located between the reference signal 3106and the switch 3116. The second input 3110 of the switch module 3102 isgenerally at electrical ground 3112, however, one skilled in therelevant art(s) will recognize that alternative embodiments existwherein the second input 3110 may not be at electrical ground 3112, butrather connected to a second signal 3118. In an alternate embodiment,the inverted value of the reference signal 3106 is connected to thesecond input 3110 of the switch module 3102.

An oscillating signal 3104 is connected to the control input 3120 of theswitch module 3102. Generally, in the AM mode, the oscillating signal3104 is not modulated, but a person skilled in the relevant art(s) willrecognize that there are embodiments wherein the oscillating signal 3104may be frequency modulated or phase modulated, but these will not bedescribed herein. The oscillating signal 3104 can be a sinusoidal wave,a rectangular wave, a triangular wave, a pulse, or any other continuousand periodic waveform. In a preferred embodiment, it would be arectangular wave. The oscillating signal 3104 causes the switch 3116 toclose and open.

The harmonically rich signal 3114 described in section 3.3.7.1 above isfound at the output 3122 of the switch module 3102. The harmonicallyrich signal 3114 is a continuous and periodic waveform whose amplitudeis a function of the amplitude of the reference signal. In oneembodiment, the harmonically rich signal 3114 has a substantiallyrectangular waveform. As stated before, a continuous and periodicwaveform, such as a rectangular wave, has sinusoidal components(harmonics) at frequencies that are integer multiples of the fundamentalfrequency of the underlying waveform (the Fourier componentfrequencies). Thus, harmonically rich signal 3114 is composed ofsinusoidal signals at frequencies that are integer multiples of thefundamental frequency of itself. As previously described, the relativeamplitude of the harmonics of a continuous periodic waveform isgenerally a function of the ratio of the pulse width of the rectangularwave and the period of the fundamental frequency, and can be determinedby doing a Fourier analysis of the periodic waveform. When the amplitudeof the periodic waveform varies, as in the AM mode of the invention, thechange in amplitude of the periodic waveform has a proportional effecton the absolute amplitude of the harmonics. In other words, the AM isembedded on top of each of the harmonics.

The description of the switch module 3102 is substantially as follows:When the switch 3116 is “open,” the amplitude of the harmonically richsignal 3114 is substantially equal to the reference signal 3106. Whenthe oscillating signal 3104 causes the switch 3116 to become “closed,”the output 3122 of the switch module 3102 becomes connected electricallyto the second input 3110 of the switch module 3102 (e.g., ground 3112 inone embodiment), and the amplitude of the harmonically rich signal 3114becomes equal to the value of the second input 3110 (e.g., zero voltsfor the embodiment wherein the second input 3110 is connected toelectrical ground 3112). When the oscillating signal 3104 causes theswitch 3116 to again become “open,” the amplitude of the harmonicallyrich signal 3114 again becomes substantially equal to the referencesignal 3106. Thus, the amplitude of the harmonically rich signal 3114 isat either of two signal levels, i.e., reference signal 3106 or ground3112, and has a frequency that is substantially equal to the frequencyof the oscillating signal 3104 that causes the switch 3116 to open andclose. In an alternate embodiment wherein the second input 3110 isconnected to the second signal 3118, the harmonically rich signal 3114varies between the reference signal 3106 and the second signal 3118. Oneskilled in the relevant art(s) will recognize that any one of a numberof switch module designs will fulfill the scope and spirit of thepresent invention.

In an embodiment of the invention, the switch 3116 is a semiconductordevice, such as a diode ring. In another embodiment, the switch is atransistor, such as, but not limited to, a field effect transistor(FET). In an embodiment wherein the FET is gallium arsenide (GaAs), themodule can be designed as seen in FIGS. 32A-32C, where the oscillatingsignal 3104 is connected to the gate 3202 of the GaAsFET 3201, thereference signal 3106 is connected to the source 3204, and electricalground 3112 is connected to the drain 3206 (in the embodiment whereground 3112 is selected as the value of the second input 3110 of theswitch module 3102). Since the drain and the source of GaAsFETs areinterchangeable, the reference signal 3106 can be applied to either thesource 3204 or to the drain 3206. If there is concern that there mightbe some source-drain asymmetry in the GaAsFET 3201, the switch 3116 canbe designed as shown in FIGS. 33A-33C, wherein two GaAsFETs 3302 and3304 are connected together, with the source 3310 of the first 3302connected to the drain 3312 of the second 3304, and the drain 3306 ofthe first 3302 being connected to the source 3308 of the second 3304.This design arrangement will substantially balance all asymmetries.

An alternate implementation of the design includes a “dwell capacitor”wherein one side of a capacitor is connected to the first input of theswitch and the other side of the capacitor is connected to the secondinput of the switch. The purpose of the design is to increase theapparent aperture of the pulse without actually increasing its width.For additional detail on the design and use of a dwell capacitor, seeco-pending application entitled “Method and System for Down-ConvertingElectromagnetic Signals Having Optimized Switch Structures,” Ser. No.09/293,095, filed Apr. 16, 1999, and other applications as referencedabove.

Other switch designs and implementations will be apparent to personsskilled in the relevant art(s).

The output 3122 of the switch module 3102, i.e., the harmonically richsignal 3114, can be routed to a filter 3504 in the AM mode.

3.3.8 The Summer (“I/Q” Mode).

As discussed above, the in-phase/quadrature-phase modulation (“I/Q”)mode embodiment of the invention uses a summer. See, as an example,summer 1832 in FIG. 18. The invention supports numerous embodiments ofthe summer. Exemplary embodiments of the summer 3402 (FIG. 34) aredescribed below. However, it should be understood that these examplesare provided for illustrative purposes only. The invention is notlimited to these embodiments.

3.3.8.1 Operational Description.

An “I” modulated signal 3404 and a “Q” modulated signal 3406 arecombined and an “I/Q” modulated signal 3408 is generated. Generally,both “I” and “Q” modulated signals 3404 and 3406 are harmonically richwaveforms, which are referred to as the harmonically rich “I” signal3404 and the harmonically rich “Q” signal 3406. Similarly, “I/Q”modulated signal 3408 is harmonically rich and is referred to as theharmonically rich “I/Q” signal. In one embodiment, these harmonicallyrich signals have substantially rectangular waveforms. As stated above,one skilled in the relevant art(s) will recognize the physicallimitations to and mathematical obstacles against achieving exact orperfect waveforms and it is not the intent of the present invention thata perfect waveform be generated or needed.

In a typical embodiment, the harmonically rich “I” signal 3404 and theharmonically rich “Q” signal 3406 are phase modulated, as is theharmonically rich “I/Q” signal 3408. A person skilled in the relevantart(s) will recognize that other modulation techniques, such asamplitude modulating the “I/Q” signal, may also be used in the “I/Q”mode without deviating from the scope and spirit of the invention.

As stated before, a continuous and periodic waveform, such asharmonically rich “I/Q” signal 3408, has sinusoidal components(harmonics) at frequencies that are integer multiples of the fundamentalfrequency of the underlying waveform (the Fourier componentfrequencies). Thus, harmonically rich “I/Q” signal 3408 is composed ofsinusoidal signals at frequencies that are integer multiples of thefundamental frequency of itself. These sinusoidal signals are alsomodulated substantially the same as the continuous and periodic waveformfrom which they are derived. That is, in this embodiment, the sinusoidalsignals are phase modulated, and include the information from both the“I” modulated signal and the “Q” modulated signal.

3.3.8.2 Structural Description.

The design and use of a summer 3402 is well known to those skilled inthe relevant art(s). A summer 3402 may be designed and fabricated fromdiscrete components, or it may be purchased “off the shelf.” A summer3402 accepts a harmonically rich “I” signal 3404 and a harmonically rich“Q” signal 3406, and combines them to create a harmonically rich “I/Q”signal 3408. In a preferred embodiment of the invention, theharmonically rich “I” signal 3404 and the harmonically rich “Q” signal3406 are both phase modulated. When the harmonically rich “I” signal3404 and the harmonically rich “Q” signal 3406 are both phase modulated,the harmonically rich “I/Q” signal 3408 is also phase modulated.

As stated before, a continuous and periodic waveform, such as theharmonically rich “I/Q” signal 3408, has sinusoidal components(harmonics) at frequencies that are integer multiples of the fundamentalfrequency of the underlying waveform (the Fourier componentfrequencies). Thus, the harmonically rich “I/Q” signal 3408 is composedof “I/Q” sinusoidal signals at frequencies that are integer multiples ofthe fundamental frequency of itself. These “I/Q” sinusoidal signals arealso phase modulated substantially the same as the continuous andperiodic waveform from which they are derived (i.e., the harmonicallyrich “I/Q” signal 3408).

The output of the summer 3402 is then routed to a filter 3504.

3.3.9 The Filter (FM, PM, AM, and “I/Q” Modes).

As discussed above, all modulation mode embodiments of the invention usea filter. See, as an example, filter 1218 in FIG. 12, filter 1414 inFIG. 14, filter 1618 in FIG. 16, and filter 1836 in FIG. 18. Theinvention supports numerous embodiments of the filter. Exemplaryembodiments of the filter 3504 (FIG. 35) are described below. However,it should be understood that these examples are provided forillustrative purposes only. The invention is not limited to theseembodiments.

3.3.9.1 Operational Description.

A modulated signal with a harmonically rich waveform 3502 is accepted.It is referred to as the harmonically rich signal 3502. As stated above,a continuous and periodic waveform, such as the harmonically rich signal3502, is comprised of sinusoidal components (harmonics) at frequenciesthat are integer multiples of the fundamental frequency of theunderlying waveform from which they are derived. These are called theFourier component frequencies. In one embodiment of the invention, theundesired harmonic frequencies are removed, and the desired frequency3506 is output. In an alternate embodiment, a plurality of harmonicfrequencies are output.

The harmonic components of the harmonically rich signal 3502 aremodulated in the same manner as the harmonically rich signal 3502itself. That is, if the harmonically rich signal 3502 is frequencymodulated, all of the harmonic components of that signal are alsofrequency modulated. The same is true for phase modulation, amplitudemodulation, and “I/Q” modulation.

3.3.9.2 Structural Description.

The design and use of a filter 3504 is well known to those skilled inthe relevant art(s). A filter 3504 may be designed and fabricated fromdiscrete components or it may be purchased “off the shelf.” The filter3504 accepts the harmonically rich signal 3502 from the switch module2802 or 3102 in the FM, PM, and AM modes, and from the summer 3402 inthe “I/Q” mode. The harmonically rich signal 3502 is a continuous andperiodic waveform. As such, it is comprised of sinusoidal components(harmonics) that are at frequencies that are integer multiples of thefundamental frequency of the underlying harmonically rich signal 3502.The filter 3504 removes those sinusoidal signals having undesiredfrequencies. The signal 3506 that remains is at the desired frequency,and is called the desired output signal 3506.

To achieve this result, according to an embodiment of the invention, afilter 3504 is required to filter out the unwanted harmonics of theharmonically rich signal 3502.

The term “Q” is used to represent the ratio of the center frequency ofthe desired output signal 3506 to the half power band width. Looking atFIG. 36 we see a desired frequency 3602 of 900 MHz. The filter 3504 isused to ensure that only the energy at that frequency 3602 istransmitted. Thus, the bandwidth 3604 at half power (the so-called “3 dBdown” point) should be as narrow as possible. The ratio of frequency3602 to bandwidth 3604 is defined as “Q.” As shown on FIG. 36, if the “3dB down” point is at plus or minus 15 MHz, the value of Q will be900÷(15+15) or 30. With the proper selection of elements for anyparticular frequency, Qs on the order of 20 or 30 are achievable.

For crisp broadcast frequencies, it is desired that Q be as high aspossible and practical, based on the given application and environment.The purpose of the filter 3504 is to filter out the unwanted harmonicsof the harmonically rich signal. The circuits are tuned to eliminate allother harmonics except for the desired frequency 3506 (e.g., the 900 MHzharmonic 3602). Turning now to FIGS. 37A and 37B, we see examples offilter circuits. One skilled in the relevant art(s) will recognize thata number of filter designs will accomplish the desired goal of passingthe desired frequency while filtering the undesired frequencies.

FIG. 37A illustrates a circuit having a capacitor in parallel with aninductor and shunted to ground. In FIG. 37B, a capacitor is in serieswith an inductor, and a parallel circuit similar to that in FIG. 37A isconnected between the capacitor and inductor and shunted to ground.

The modulated signal at the desired frequency 3506 may then be routed tothe transmission module 3804.

3.3.10 The Transmission Module (FM, PM, AM, and “I/Q” Modes).

As discussed above, the modulation mode embodiments of the inventionpreferably use a transmission module. See, as an example, transmissionmodule 1222 in FIG. 12, transmission module 1418 in FIG. 14,transmission module 1622 in FIG. 16, and transmission module 1840 inFIG. 18. The transmission module is optional, and other embodiments maynot include a transmission module. The invention supports numerousembodiments of the transmission module. Exemplary embodiments of thetransmission module 3804 (FIG. 38) are described below. However, itshould be understood that these examples are provided for illustrativepurposes only. The invention is not limited to these embodiments.

3.3.10.1 Operational Description.

A modulated signal at the desired frequency 3802 is accepted and istransmitted over the desired medium, such as, but not limited to,over-the-air broadcast or point-to-point cable.

3.3.10.2 Structural Description.

The transmission module 3804 receives the signal at the desired EMfrequency 3802. If it is intended to be broadcast over the air, thesignal may be routed through an optional antenna interface and then tothe antenna for broadcast. If it is intended for the signal to betransmitted over a cable from one point to another, the signal may berouted to an optional line driver and out through the cable. One skilledin the relevant art(s) will recognize that other transmission media maybe used.

3.3.11 Other Implementations.

The implementations described above are provided for purposes ofillustration. These implementations are not intended to limit theinvention. Other implementation embodiments are possible and covered bythe invention, such as but not limited to software, software/hardware,and firmware implementations of the systems and components of theinvention. Alternate implementations and embodiments, differing slightlyor substantially from those described herein, will be apparent topersons skilled in the relevant art(s) based on the teachings containedherein. Such alternate implementations fall within the scope and spiritof the present invention.

4. Harmonic Enhancement.

4.1 High Level Description.

This section (including its subsections) provides a high-leveldescription of harmonic enhancement according to the present invention.In particular, pulse shaping is described at a high-level. Also, astructural implementation for achieving this process is described at ahigh-level. This structural implementation is described herein forillustrative purposes, and is not limiting. In particular, the processdescribed in this section can be achieved using any number of structuralimplementations, one of which is described in this section. The detailsof such structural implementations will be apparent to persons skilledin the relevant art(s) based on the teachings contained herein.

It is noted that some embodiments of the invention include harmonicenhancement, whereas other embodiments do not.

4.1.1 Operational Description.

To better understand the generation and extraction of harmonics, and thepurpose behind shaping the waveforms to enhance the harmonics, thefollowing discussion of Fourier analysis as it applies to the presentinvention is offered.

A discovery made by Baron Jean B. J. Fourier (1768-1830) showed thatcontinuous and periodic waveforms are comprised of a plurality ofsinusoidal components, called harmonics. More importantly, the frequencyof these components are integer multiples of the frequency of theoriginal waveform (called the fundamental frequency). The amplitude ofeach of these component waveforms depends on the shape of the originalwaveform. The derivations and proofs of Baron Fourier's analysis arewell known to those skilled in the relevant art(s).

The most basic waveform which is continuous and periodic is a sine wave.It has but one harmonic, which is at the fundamental frequency. This isalso called the first harmonic. Since it only has one component, theamplitude of the harmonic component is equal to the amplitude of theoriginal waveform, i.e., the sine wave itself. The sine wave is notconsidered to be “harmonically rich.”

An impulse train is the other extreme case of a periodic waveform.Mathematically, it is considered to have zero width. The mathematicalanalysis in this case shows that there are harmonics at all multiples ofthe frequency of the impulse. That is, if the impulse has a frequency ofF_(i), then the harmonics are sinusoidal waves at 1·F_(i), 2·F_(i),3·F_(i), 4·F_(i), etc. As the analysis also shows in this particularcase, the amplitude of all of the harmonics are equal. This is indeed, a“harmonically rich” waveform, but is realistically impractical withcurrent technology.

A more typical waveform is a rectangular wave, which is a series ofpulses. Each pulse will have a width (called a pulse width, or “τ”), andthe series of pulses in the waveform will have a period (“T” which isthe inverse of the frequency, i.e., T=1/F_(r), where “F_(r)” is thefundamental frequency of the rectangular wave). One form of rectangularwave is the square wave, where the signal is at a first state (e.g.,high) for the same amount of time that it is at the second state (e.g.,low). That is, the ratio of the pulse width to period (τ/T) is 0.5.Other forms of rectangular waves, other than square waves, are typicallyreferred to simply as “pulses,” and have τ/T<0.5 (i.e., the signal willbe “high” for a shorter time than it is “low”). The mathematicalanalysis shows that there are harmonics at all of the multiples of thefundamental frequency of the signal. Thus, if the frequency of therectangular waveform is F, then the frequency of the first harmonic is1·F_(r), the frequency of the second harmonic is 2·F_(r), the frequencyof the third harmonic is 3·F_(r), and so on. There are some harmonicsfor which the amplitude is zero. In the case of a square wave, forexample, the “null points” are the even harmonics. For other values ofτ/T, the “null points” can be determined from the mathematicalequations. The general equation for the amplitude of the harmonics in arectangular wave having an amplitude of A_(pulse) is as follows:Amplitude(n ^(th) harmonic)=A _(n) ={[A_(pulse)][(2/π)/n]sin[n·π·(τ/T)]}  Eq. 1Table 6000 of FIG. 60 shows the amplitudes of the first fifty harmonicsfor rectangular waves having six different τ/T ratios. The τ/T ratiosare 0.5 (a square wave), 0.25, 0.10, 0.05, 0.01, and 0.005. (One skilledin the relevant art(s) will recognize that A_(pulse) is set to unity formathematical comparison.) From this limited example, it can be seen thatthe ratio of pulse width to period is a significant factor indetermining the relative amplitudes of the harmonics. Notice too, thatfor the case where τ/T=0.5 (i.e., a square wave), the relationshipstated above (i.e., only odd harmonics are present) holds. Note that asτ/T becomes small (i.e., the pulse approaches an impulse), theamplitudes of the harmonics becomes substantially “flat.” That is, thereis very little decrease in the relative amplitudes of the harmonics. Oneskilled in the relevant art(s) will understand how to select the desiredpulse width for any given application based on the teachings containedherein. It can also be shown mathematically and experimentally that if asignal with a continuous and periodic waveform is modulated, thatmodulation is also present on every harmonic of the original waveform.

From the foregoing, it can be seen how pulse width is an importantfactor in assuring that the harmonic waveform at the desired outputfrequency has sufficient amplitude to be useful without requiringelaborate filtering or unnecessary amplification.

Another factor in assuring that the desired harmonic has sufficientamplitude is how the switch 2816 and 3116 (FIGS. 28A and 31A) in theswitch module 2802 and 3102 responds to the control signal that causesthe switch to close and to open (i.e., the modulated oscillating signal2804 of FIG. 28 and the oscillating signal 3104 of FIG. 31). In general,switches have two thresholds. In the case of a switch that is normallyopen, the first threshold is the voltage required to cause the switch toclose. The second threshold is the voltage level at which the switchwill again open. The convention used herein for ease of illustration anddiscussion (and not meant to be limiting) is for the case where theswitch is closed when the control signal is high, and open when thecontrol signal is low. It would be apparent to one skilled in therelevant art(s) that the inverse could also be used. Typically, thesevoltages are not identical, but they may be. Another factor is howrapidly the switch responds to the control input once the thresholdvoltage has been applied. The objective is for the switch to close andopen such that the bias/reference signal is “crisply” gated. That is,preferably, the impedance through the switch must change from a highimpedance (an open switch) to a low impedance (a closed switch) and backagain in a very short time so that the output signal is substantiallyrectangular.

It is an objective of this invention in the transmitter embodiment thatthe intelligence in the information signal is to be transmitted. Thatis, the information is modulated onto the transmitted signal. In the FMand PM modes, to achieve this objective, the information signal is usedto modulate the oscillating signal 2804. The oscillating signal 2804then causes the switch 2816 to close and open. The information that ismodulated onto the oscillating signal 2804 must be faithfully reproducedonto the signal that is output from the switch circuit (i.e., theharmonically rich signal 2814). For this to occur efficiently, inembodiments of the invention, the switch 2816 preferably closes andopens crisply so that the harmonically rich signal 2814 changes rapidlyfrom the bias/reference signal 2806 (or 3106) to ground 2812 (or thesecond signal level 2818 in the alternate embodiment). This rapid riseand fall time is desired so that the harmonically rich signal 2814 willbe “harmonically rich.” (In the case of AM, the oscillating signal 3104is not modulated, but the requirement for “crispness” still applies.)

For the switch 2816 to close and open crisply, the oscillating signal2804 must also be crisp. If the oscillating signal 2804 is sinusoidal,the switch 2816 will open and close when the threshold voltages arereached, but the pulse width of the harmonically rich signal 2814 maynot be as small as is needed to ensure the amplitude of the desiredharmonic of the harmonically rich signal 2814 is sufficiently high toallow transmission without elaborate filtering or unnecessaryamplification. Also, in the embodiment wherein the switch 2816 is aGaAsFET 2901, if the oscillating signal 2804 that is connected to thegate 2902 of the GaAsFET 2901 (i.e., the signal that causes the switch2816 to close and open) is a sinusoidal wave, the GaAsFET 2901 will notcrisply close and open, but will act more like an amplifier than aswitch. (That is, it will conduct during the time that the oscillatingsignal is rising and falling below the threshold voltages, but will notbe a “short.”) In order to make use of the benefits of a GaAsFET'scapability to close and open at high frequencies, the oscillating signal2804 connected to the gate 2902 preferably has a rapid rise and falltime. That is, it is preferably a rectangular waveform, and preferablyhas a pulse width to period ratio the same as the pulse width to periodratio of the harmonically rich signal 2814.

As stated above, if a signal with a continuous and periodic waveform ismodulated, that modulation occurs on every harmonic of the originalwaveform. Thus, in the FM and PM modes, when the information ismodulated onto the oscillating signal 2804 and the oscillating signal2804 is used to cause the switch 2816 to close and open, the resultingharmonically rich signal 2814 that is output from the switch module 2802will also be modulated. If the oscillating signal 2804 is crisp, theswitch 2816 will close and open crisply, the harmonically rich signal2814 will be harmonically rich, and each of the harmonics of theharmonically rich signal 2814 will have the information modulated on it.

Because it is desired that the oscillating signal 2804 be crisp,harmonic enhancement may be needed in some embodiments. Harmonicenhancement may also be called “pulse shaping” since the purpose is toshape the oscillating signal 2804 into a string of pulses of a desiredpulse width. If the oscillating signal is sinusoidal, harmonicenhancement will shape the sinusoidal signal into a rectangular (orsubstantially rectangular) waveform with the desired pulse width toperiod ratio. If the oscillating signal 2804 is already a square wave ora pulse, harmonic enhancement will shape it to achieve the desired ratioof pulse width to period. This will ensure an efficient transfer of themodulated information through the switch.

Three exemplary embodiments of harmonic enhancement are described belowfor illustrative purposes. However, the invention is not limited tothese embodiments. Other embodiments will be apparent to persons skilledin the relevant art(s) based on the teachings contained herein.

4.1.2 Structural Description.

The shape of the oscillating signal 2804 causes the switch 2816 to closeand open. The shape of the oscillating signal 2804 and the selection ofthe switch 2816 will determine how quickly the switch 2816 closes andopens, and how long it stays closed compared to how long it stays open.This then will determine the “crispness” of the harmonically rich signal2814. (That is, whether the harmonically rich signal 2814 issubstantially rectangular, trapezoidal, triangular, etc.) As shownabove, in order to ensure that the desired harmonic has the desiredamplitude, the shape of the oscillating signal 2804 should besubstantially optimized.

The harmonic enhancement module (HEM) 4602 (FIG. 46) is also referred toas a “pulse shaper.” It “shapes” the oscillating signals 2804 and 3104that drive the switch modules 2802 and 3102 described in sections3.3.6-3.3.6.2 and 3.3.7-3.3.7.2. Harmonic enhancement module 4602preferably transforms a continuous and periodic waveform 4604 into astring of pulses 4606. The string of pulses 4606 will have a period,“T,” determined by both the frequency of the continuous and periodicwaveform 4604 and the design of the pulse shaping circuit within theharmonic enhancement module 4602. Also, each pulse will have a pulsewidth, “τ,” determined by the design of the pulse shaping circuit. Theperiod of the pulse stream, “T,” determines the frequency of the switchclosing (the frequency being the inverse of the period), and the pulsewidth of the pulses, “r,” determines how long the switch stays closed.

In the embodiment described above in sections 3.3.6-3.3.6.2 (and3.3.7-3.3.7.2), when the switch 2816 (or 3116) is open, the harmonicallyrich signal 2814 (or 3114) will have an amplitude substantially equal tothe bias signal 2806 (or reference signal 3106). When the switch 2816(or 3116) is closed, the harmonically rich signal 2814 (or 3114) willhave an amplitude substantially equal to the potential of signal 2812 or2818 (or 3112 or 3118) of the second input 2810 (or 3110) of the switchmodule 2802 (or 3102). Thus, for the case where the oscillating signal2804 (or 3104) driving the switch module 2802 (or 3102) is substantiallyrectangular, the harmonically rich signal 2814 (or 3114) will havesubstantially the same frequency and pulse width as the shapedoscillating signal 2804 (or 3104) that drives the switch module 2802 (or3102). This is true for those cases wherein the oscillating signal 2804(or 3104) is a rectangular wave. One skilled in the relevant art(s) willunderstand that the term “rectangular wave” can refer to all waveformsthat are substantially rectangular, including square waves and pulses.

The purpose of shaping the signal is to control the amount of time thatthe switch 2816 (or 3116) is closed. As stated above, the harmonicallyrich signal 2814 (or 3114) has a substantially rectangular waveform.Controlling the ratio of the pulse width of the harmonically rich signal2814 (or 3114) to its period will result in the shape of theharmonically rich signal 2814 (or 3114) being substantially optimized sothat the relative amplitudes of the harmonics are such that the desiredharmonic can be extracted without unnecessary and elaborateamplification and filtering.

4.2 Exemplary Embodiments.

Various embodiments related to the method(s) and structure(s) describedabove are presented in this section (and its subsections). Theseembodiments are described herein for purposes of illustration, and notlimitation. The invention is not limited to these embodiments. Alternateembodiments (including equivalents, extensions, variations, deviations,etc., of the embodiments described herein) will be apparent to personsskilled in the relevant art(s) based on the teachings contained herein.The invention is intended and adapted to include such alternateembodiments.

4.2.1 First Embodiment: When a Square Wave Feeds the HarmonicEnhancement Module to Create One Pulse per Cycle.

4.2.1.1 Operational Description.

According to this embodiment, a continuous periodic waveform 4604 isreceived and a string of pulses 4606 is output. The continuous periodicwaveform 4604 may be a square wave or any other continuous periodicwaveform that varies from a value recognized as a “digital low” to avalue recognized as a “digital high.” One pulse is generated per cycleof the continuous and periodic waveform 4604. The description givenherein will be for the continuous periodic waveform 4604 that is asquare wave, but one skilled in the relevant art(s) will appreciate thatother waveforms may also be “shaped” into waveform 4606 by thisembodiment.

4.2.1.2 Structural Description.

In this first embodiment of a harmonic enhancement module 4602, hereinafter referred to as a pulse shaping circuit 4602, a continuous periodicwaveform 4604 that is a square wave is received by the pulse shapingcircuit 4602. The pulse shaping circuit 4602 is preferably comprised ofdigital logic devices that result in a string of pulses 4606 beingoutput that has one pulse for every pulse in the continuous periodicwaveform 4604, and preferably has a τ/T ratio less than 0.5.

4.2.2 Second Embodiment: When a Square Wave Feeds the HarmonicEnhancement Module to Create Two Pulses per Cycle

4.2.2.1 Operational Description.

In this embodiment, a continuous periodic waveform 4604 is received anda string of pulses 4606 is output. In this embodiment, there are twopulses output for every period of the continuous periodic waveform 4604.The continuous periodic waveform 4604 may be a square wave or any othercontinuous periodic waveform that varies from a value recognized as a“digital low” to a value recognized as a “digital high.” The descriptiongiven herein will be for a continuous periodic waveform 4604 that is asquare wave, but one skilled in the relevant art(s) will appreciate thatother waveforms may also be “shaped” into waveform 4606 by thisembodiment.

4.2.2.2 Structural Description.

In this second embodiment of a pulse shaping circuit 4602, a continuousperiodic waveform 4604 that is a square wave is received by the pulseshaping circuit 4602. The pulse shaping circuit 4602 is preferablycomprised of digital logic devices that result in a string of pulses4606 being output that has two pulses for every pulse in the continuousperiodic waveform 4604, and preferably has a τ/T ratio less than 0.5.

4.2.3 Third Embodiment: When Any Waveform Feeds the Module.

4.2.3.1 Operational Description.

In this embodiment, a continuous periodic waveform 4604 of any shape isreceived and a string of pulses 4606 is output.

4.2.3.2 Structural Description.

In this third embodiment of a pulse shaping circuit 4602, a continuousperiodic waveform 4604 of any shape is received by the pulse shapingcircuit 4602. The pulse shaping circuit 4602 is preferably comprised ofa series of stages, each stage shaping the waveform until it issubstantially a string of pulses 4606 with preferably a τ/T ratio lessthan 0.5.

4.2.4 Other Embodiments.

The embodiments described above are provided for purposes ofillustration. These embodiments are not intended to limit the invention.Alternate embodiments, differing slightly or substantially from thosedescribed herein, will be apparent to persons skilled in the relevantart(s) based on the teachings contained herein. Such alternateembodiments fall within the scope and spirit of the present invention.

4.3 Implementation Examples.

Exemplary operational and/or structural implementations related to themethod(s), structure(s), and/or embodiments described above arepresented in this section (and its subsections). These components andmethods are presented herein for purposes of illustration, and notlimitation. The invention is not limited to the particular examples ofcomponents and methods described herein. Alternatives (includingequivalents, extensions, variations, deviations, etc., of thosedescribed herein) will be apparent to persons skilled in the relevantart(s) based on the teachings contained herein. Such alternatives fallwithin the scope and spirit of the present invention.

4.3.1 First Digital Logic Circuit.

An exemplary implementation of the first embodiment described insections 4.2.1-4.2.1.2 is illustrated in FIG. 39. In particular, thecircuit shown in FIG. 39A is a typical circuit design for a pulseshaping circuit 4602 using digital logic devices. Also shown in FIGS.39B-39D are representative waveforms at three nodes within the circuit.In this embodiment, pulse shaper 3900 uses an inverter 3910 and an ANDgate 3912 to produce a string of pulses. An inverter, such as inverter3910, changes the sign of the input, and an AND gate, such as AND gate3912, outputs a digital “high’ when all of the input signals are digital“highs.” The input to pulse shaper 3900 is waveform 3902, and, forillustrative purposes, is shown here as a square wave. The output ofinverter 3910 is waveform 3904, which is also a square wave. However,because of the circuitry of the inverter 3910, there is a delay betweenthe application of the input and the corresponding sign change of theoutput. If waveform 3902 starts “low,” waveform 3904 will be “high”because it has been inverted by inverter 3910. When waveform 3902switches to “high,” AND gate 3912 will momentarily see two “high”signals, thus causing its output waveform 3906 to be “high.” Wheninverter 3910 has inverted its input (waveform 3902) and caused waveform3904 to become “low,” AND gate 3912 will then see only one “high”signal, and the output waveform 3906 will become “low.” Thus, the outputwaveform 3906 will be “high” for only the period of time that bothwaveforms 3902 and 3904 are high, which is the time delay of theinverter 3910. Accordingly, as is apparent from FIGS. 39B-39D, pulseshaper 3900 receives a square wave and generates a string of pulses,with one pulse generated per cycle of the square wave.

4.3.2 Second Digital Logic Circuit.

An exemplary implementation of the second embodiment described insections 4.2.2-4.2.2.2 is illustrated in FIG. 40. In particular, thecircuit of FIG. 40A is a typical circuit design for a pulse shapingcircuit 4602 using digital logic devices. Also shown in FIGS. 40B-40Dare representative waveforms at three nodes within the circuit. In thisembodiment, pulse shaping circuit 4000 uses an inverter 4010 and anexclusive NOR (XNOR) gate 4012. An XNOR, such as XNOR 4012, outputs adigital “high” when both inputs are digital “highs” and when bothsignals are digital “lows.” Waveform 4002, which is shown here as asquare wave identical to that shown above as waveform 3902, begins inthe “low” state. Therefore, the output of inverter 4010 will begin atthe “high” state. Thus, XNOR gate 4012 will see one “high” input and one“low” input, and its output waveform 4006 will be “low.” When waveform4002 changes to “high,” XNOR gate 4012 will have two “high” inputs untilthe waveform 4004 switches to “low.” Because it sees two “high” inputs,its output waveform 4006 will be “high.” When waveform 4004 becomes“low,” XNOR gate 4012 will again see one “high” input (waveform 4002)and one “low” input (waveform 4004). When waveform 4002 switches back to“low,” XNOR gate 4012 will see two “low” inputs, and its output willbecome “high.” Following the time delay of inverter 4010, waveform 4004will change to “high,” and XNOR gate 4012 will again see one “high”input (waveform 4004) and one “low” input (waveform 4002). Thus,waveform 4006 will again switch to “low.” Accordingly, as is apparentfrom FIGS. 40B-40D, pulse shaper 4000 receives a square wave andgenerates a string of pulses, with two pulses generated per cycle of thesquare wave.

4.3.3 Analog Circuit.

An exemplary implementation of the third embodiment described insections 4.2.3-4.2.3.2 is illustrated in FIG. 41. In particular, thecircuit shown in FIG. 41 is a typical pulse shaping circuit 4602 wherean input signal 4102 is shown as a sine wave. Input signal 4102 feedsthe first circuit element 4104, which in turn feeds the second, and soon. Typically, three circuit elements 4104 produce incrementally shapedwaveforms 4120, 4122, and 4124 before feeding a capacitor 4106. Theoutput of capacitor 4106 is shunted to ground 4110 through a resistor4108 and also feeds a fourth circuit element 4104. An output signal 4126is a pulsed output, with a frequency that is a function of the frequencyof input signal 4102.

An exemplary circuit for circuit elements 4104 is shown in FIG. 43.Circuit 4104 is comprised of an input 4310, an output 4312, four FETs4302, two diodes 4304, and a resistor 4306. One skilled in the relevantart(s) would recognize that other pulse shaping circuit designs couldalso be used without deviating from the scope and spirit of theinvention.

4.3.4 Other Implementations.

The implementations described above are provided for purposes ofillustration. These implementations are not intended to limit theinvention. Alternate implementations, differing slightly orsubstantially from those described herein, will be apparent to personsskilled in the relevant art(s) based on the teachings contained herein.Such alternate implementations fall within the scope and spirit of thepresent invention.

5. Amplifier Module.

5.1 High Level Description.

This section (including its subsections) provides a high-leveldescription of the amplifier module according to the present invention.In particular, amplification is described at a high-level. Also, astructural implementation for achieving signal amplification isdescribed at a high-level. This structural implementation is describedherein for illustrative purposes, and is not limiting. In particular,the process described in this section can be achieved using any numberof structural implementations, one of which is described in thissection. The details of such structural implementations will be apparentto persons skilled in the relevant art(s) based on the teachingscontained herein.

5.1.1 Operational Description.

Even though the present invention is intended to be used withoutrequiring amplification, there may be circumstance when, in theembodiment of the present invention wherein it is being used as atransmitter, it may prove desirable to amplify the modulated signalbefore it is transmitted. In another embodiment of the invention whereinit is being used as a stable signal source for a frequency or phasecomparator, it may also be desirable to amplify the resultant signal atthe desired frequency.

The requirement may come about for a number of reasons. A first may bethat the bias/reference signal is too low to support the desired use. Asecond may be because the desired output frequency is very high relativeto the frequency of the oscillating signal that controls the switch. Athird reason may be that the shape of the harmonically rich signal issuch that the amplitude of the desired harmonic is low.

In the first case, recall that the amplitude of the bias/referencesignal determines the amplitude of the harmonically rich signal which ispresent at the output of the switch circuit. (See sections 3.3.6-3.3.6.2and 3.3.7-3.3.7.2.) Further recall that the amplitude of theharmonically rich signal directly impacts the amplitude of each of theharmonics. (See the equation in section 4.1, above.)

In the second instance, if the frequency of the oscillating signal isrelatively low compared to the desired output frequency of theup-converter, a high harmonic will be needed. As an example, if theoscillating signal is 60 MHz, and the desired output frequency is at 900MHz, the 15^(th) harmonic will be needed. In the case where τ/T is 0.1,it can be seen from Table 6000 of FIG. 60 that the amplitude of the15^(th) harmonic (A₁₅) is 0.0424, which is 21.5% of the amplitude of thefirst harmonic (A₁=0.197). There may-be instances wherein this isinsufficient for the desired use, and consequently it must be amplified.

The third circumstance wherein the amplitude of the output may need tobe amplified is when the shape of the harmonically rich signal in not“crisp” enough to provide harmonics with enough amplitude for thedesired purpose. If, for example, the harmonically rich signal issubstantially triangular, and given the example above where theoscillating signal is 60 MHz and the desired output signal is 900 MHz,the 15^(th) harmonic of the triangular wave is 0.00180. This issignificantly lower than the amplitude of the 15^(th) harmonic of the“0.1” rectangular wave (shown above to be 0.0424) and can bemathematically shown to be 0.4% of the amplitude of the 1^(st) harmonicof the triangular wave (which is 0.405). Thus, in this example, the1^(st) harmonic of the triangular wave has an amplitude that is largerthan the amplitude of the 1^(st) harmonic of the “0.1” rectangular wave,but at the 15^(th) harmonic, the triangular wave is significantly lowerthan the “0.1” rectangular wave.

Another reason that the desired harmonic may need to be amplified isthat circuit elements such as the filter may cause attenuation in theoutput signal for which a designer may wish to compensate.

The desired output signal can be amplified in a number of ways. One isto amplify the bias/reference signal to ensure that the amplitude of theharmonically rich wave form is high. A second is to amplify theharmonically rich waveform itself. A third is to amplify the desiredharmonic only. The examples given herein are for illustrative purposesonly and are not meant to be limiting on the present invention. Othertechniques to achieve amplification of the desired output signal wouldbe apparent to those skilled in the relevant art(s).

5.1.2 Structural Description.

In one embodiment, a linear amplifier is used to amplify thebias/reference signal. In another embodiment, a linear amplifier is usedto amplify the harmonically rich signal. And in yet another embodiment,a linear amplifier is used to amplify the desired output signal. Otherembodiments, including the use of non-linear amplifiers, will beapparent to persons skilled in the relevant art(s).

5.2 Exemplary Embodiment.

An embodiment related to the method(s) and structure(s) described aboveis presented in this section (and its subsections). This embodiment isdescribed herein for purposes of illustration, and not limitation. Theinvention is not limited to this embodiment. Alternate embodiments(including equivalents, extensions, variations, deviations, etc., of theembodiment described herein) will be apparent to persons skilled in therelevant art(s) based on the teachings contained herein. The inventionis intended and adapted to include such alternate embodiments.

5.2.1 Linear Amplifier.

The exemplary linear amplifier described herein will be directed towardsan amplifier composed of solid state electronic devices to be insertedin the circuit at one or more points. Other amplifiers suitable for usewith the invention will be apparent to persons skilled in the relevantart(s). As shown in FIG. 47, an amplifier module 4702 receives a signalrequiring amplification 4704 and outputs an amplified signal 4706. Itwould be apparent to one skilled in the relevant art(s) that a pluralityof embodiments may be employed without deviating from the scope andintent of the invention described herein.

5.2.1.1 Operational Description.

The desired output signal can be amplified in a number of ways. Suchamplification as described in the section may be in addition to thetechniques described above to enhance the shape of the harmonically richsignal by pulse shaping of the oscillating signal that causes the switchto close and open.

5.2.1.2 Structural Description.

In one embodiment, a linear amplifier is placed between thebias/reference signal and the switch module. This will increase theamplitude of the bias/reference signal, and as a result, will raise theamplitude of the harmonically rich signal that is the output of theswitch module. This will have the effect of not only raising theamplitude of the harmonically rich signal, it will also raise theamplitude of all of the harmonics. Some potential limitation of thisembodiment are: the amplified bias/reference signal may exceed thevoltage design limit for the switch in the switch circuit; theharmonically rich signal coming out of the switch circuit may have anamplitude that exceeds the voltage design limits of the filter; and/orunwanted distortion may occur from having to amplify a wide bandwidthsignal.

A second embodiment employs a linear amplifier between the switch moduleand the filter. This will raise the amplitude of the harmonically richsignal. It will also raise the amplitude of all of the harmonics of thatsignal. In an alternate implementation of this embodiment, the amplifieris tuned so that it only amplifies the desired frequencies. Thus, itacts both as an amplifier and as a filter. A potential limitation ofthis embodiment is that when the harmonically rich signal is amplifiedto raise a particular harmonic to the desired level the amplitude of thewhole waveform is amplified as well. For example, in the case where theamplitude of the pulse, A_(pulse), is equal to 1.0, to raise the 15^(th)harmonic from 0.0424 volts to 0.5 volts, the amplitude of each pulse inthe harmonically rich signal, A_(pulse), will increase from 1.0 to 11.8volts. This may well exceed the voltage design limit of the filter.

A third embodiment of an amplifier module will place a linear amplifierbetween the filter and the transmission module. This will only raise theamplitude of the desired harmonic, rather than the entire harmonicallyrich signal.

Other embodiments, such as the use of non-linear amplifiers, will beapparent to one skilled in the relevant art(s), and will not bedescribed herein.

5.2.2 Other Embodiments.

The embodiments described above are provided for purposes ofillustration. These embodiments are not intended to limit the invention.Alternate embodiments, differing slightly or substantially from thosedescribed herein, will be apparent to persons skilled in the relevantart(s) based on the teachings contained herein. Such alternateembodiments fall within the scope and spirit of the present invention.

5.3 Implementation Examples.

Exemplary operational and/or structural implementations related to themethod(s), structure(s), and/or embodiments described above arepresented in this section (and its subsections). These components andmethods are presented herein for purposes of illustration, and notlimitation. The invention is not limited to the particular examples ofcomponents and methods described herein. Alternatives (includingequivalents, extensions, variations, deviations, etc., of thosedescribed herein) will be apparent to persons skilled in the relevantart(s) based on the teachings contained herein. Such alternatives fallwithin the scope and spirit of the present invention.

5.3.1 Linear Amplifier.

Although described below as if it were placed after the filter, theamplifier may also be placed before the filter without deviating fromthe intent of the invention.

5.3.1. Operational Description.

According to embodiments of the invention, a linear amplifier receives afirst signal at a first amplitude, and outputs a second signal at asecond amplitude, wherein the second signal is proportional to the firstsignal. It is a objective of an amplifier that the information embeddedonto the first signal waveform will also be embedded onto the secondsignal. Typically, it is desired that there be as little distortion inthe information as possible.

In a preferred embodiment, the second signal is higher in amplitude thanthe first signal, however, there may be implementations wherein it isdesired that the second signal be lower than the first signal (i.e., thefirst signal will be attenuated).

5.3.1.2 Structural Description.

The design and use of a linear amplifier is well known to those skilledin the relevant art(s). A linear amplifier may be designed andfabricated from discrete components, or it may be purchased “off theshelf.”

Exemplary amplifiers are seen in FIG. 48. In the exemplary circuitdiagram of FIG. 48A, six transistors are used in a wideband amplifier.In the more basic exemplary circuit of FIG. 48B, the amplifier iscomposed of one transistor, four resistors, and a capacitor. Thoseskilled in the relevant art(s) will recognize that numerous alternativedesigns may be used.

5.3.2 Other Implementations.

The implementations described above are provided for purposes ofillustration. These implementations are not intended to limit theinvention. Alternate implementations, differing slightly orsubstantially from those described herein, will be apparent to personsskilled in the relevant art(s) based on the teachings contained herein.Such alternate implementations fall within the scope and spirit of thepresent invention.

6. Receiver/Transmitter System.

The present invention is for a method and system for up-conversion ofelectromagnetic signals. In one embodiment, the invention is a source ofa stable high frequency reference signal. In a second embodiment, theinvention is a transmitter.

This section describes a third embodiment. In the third embodiment, thetransmitter of the present invention to be used in areceiver/Transmitter communications system. This third embodiment mayalso be referred to as the communications system embodiment, and thecombined receiver/transmitter circuit is referred to as a “transceiver.”There are several alternative enhancements to the communications systemsembodiment.

The following sections describe systems and methods related to exemplaryembodiments for a receiver/transmitter system. It should be understoodthat the invention is not limited to the particular embodimentsdescribed below. Equivalents, extensions, variations, deviations, etc.,of the following will be apparent to persons skilled in the relevantart(s) based on the teachings contained herein. Such equivalents,extensions, variations, deviations, etc., are within the scope andspirit of the present invention.

6.1 High Level Description.

This section provides a high-level description of a receiver/transmittersystem according to the present invention. The implementations aredescribed herein for illustrative purposes, and are not limiting. Inparticular, any number of functional and structural implementations maybe used, several of which are described in this section. The details ofsuch functional and structural implementations will be apparent topersons skilled in the relevant art(s) based on the teachings containedherein.

According to a first embodiment of the transmitter of the presentinvention is used with a traditional superheterodyne receiver. In thisembodiment, the transmitter and the receiver can operate either in afull-duplex mode or in a half-duplex mode. In a full duplex mode, thetransceiver can transmit and receive simultaneously. In the half-duplexmode, the transceiver can either transmit or receive, but cannot do bothsimultaneously. The full-duplex and the half-duplex modes will bediscussed together for this embodiment.

A second embodiment of the transceiver is for the transmitter of thepresent invention to be used with a universal frequency down conversioncircuit being used as a receiver. In this embodiment the transceiver isused in a half-duplex mode.

A third embodiment of the transceiver is for the transmitter of thepresent invention to be used with a universal frequency down conversioncircuit, where the transceiver is used in a full-duplex mode.

These embodiments of the transceiver are described below.

6.2 Exemplary Embodiments and Implementation Examples.

Various embodiments related to the method(s) and structure(s) describedabove and exemplary operational and/or structural implementationsrelated to those embodiments are presented in this section (and itssubsections). These embodiments, components, and methods are describedherein for purposes of illustration, and not limitation. The inventionis not limited to these embodiments or to the particular examples ofcomponents and methods described herein. Alternatives (includingequivalents, extensions, variations, deviations, etc., of thosedescribed herein) will be apparent to persons skilled in the relevantart(s) based on the teachings contained herein. Such alternatives fallwithin the scope and spirit of the present invention, and the inventionis intended and adapted to include such alternatives.

6.2.1 First Embodiment: The Transmitter of the Present Invention BeingUsed in a Circuit with a Superheterodyne Receiver.

A typical superheterodyne receiver is shown in FIG. 49. An antenna 4904receives a signal 4902. Typically, signal 4902 is a radio frequency (RF)signal which is routed to a filter 4910 and an amplifier 4908. Thefilter 4910 removes all but a frequency range that includes the desiredfrequency, and the amplifier 4908 ensures that the signal strength willbe sufficient for further processing. The output of amplifier 4908 is asignal 4911.

A local oscillator 4914 generates an oscillating signal 4916 which iscombined with signal 4911 by mixer 4912. The output of mixer 4912 is asignal 4934 which is amplified by an amplifier 4918 and filtered by afilter 4920. The purpose of amplifier 4918 is to ensure that thestrength of signal 4934 is sufficient for further processing, and thepurpose of filter 4920 is to remove the undesired frequencies.

A second local oscillator 4924 generates a second oscillating signal4926 which is combined with the amplified/filtered signal 4934 by amixer 4922. The output of mixer 4922 is signal 4936. Again, an amplifier4928 and a filter 4930 ensure that the signal 4936 is at the desiredamplitude and frequency. The resulting signal is then routed to decoder4932 where the intelligence is extracted to obtain baseband signal 4938.

Signal 4934 is referred to as the first intermediate frequency (IF)signal, and signal 4936 is referred to as the second IF signal. Thus,the combination of local oscillator 4914 and mixer 4912 can be referredto as the first IF stage, and the combination of local oscillator 4924and mixer 4922 can be referred to as the second IF stage.

Exemplary frequencies for the circuit of FIG. 49 are as follows. Signal4902 may be 900 MHz. The oscillator signal 4916 may be at 830 MHz, whichwill result in the frequency of the first IF signal, signal 4934, beingat 70 MHz. If the second oscillating signal 4926 is at 59 MHz, thesecond IF signal, signal 4936, would be at 11 MHz. This frequency istypical of second IF frequencies.

Other superheterodyne receiver configurations are well known and thesecan be used in the transceiver embodiments of the invention. Also, theexemplary frequencies mentioned above are provide for illustrativepurposes only, and are not limiting.

FIG. 50 shows a transmitter of the present invention in a transceivercircuit with a typical superheterodyne receiver. Accordingly, FIG. 50illustrates an exemplary transceiver circuit of the invention. Thetransceiver includes a receiver module 5001, which is implemented usingany superheterodyne receiver configuration, and which is describedabove. The transceiver also includes a transmitter module 5003, which isdescribed below.

In the FM and PM modes, an information signal 5004 modulates anintermediate signal to produce the oscillating signal 5002. Oscillatingsignal 5002 is shaped by signal shaper 5010 to produce a string ofpulses 5008 (see the discussion above regarding the benefits of harmonicenhancement). The string of pulses 5008 drives the switch module 5012.In the FM/PM modes, a bias/reference signal 5006 is also received byswitch module 5012. The output of switch module 5012 is a harmonicallyrich signal 5022. Harmonically rich signal 5022 is comprised of aplurality of sinusoidal components, and is routed to a “high Q” filterthat will remove all but the desired output frequency(ies). The desiredoutput frequency 5024 is amplified by an amplifier 5016 and routed to atransmission module 5018 which outputs a transmission signal 5026 whichis routed to a duplexer 5020. The purpose of duplexer 5020 is to permita single antenna to be used simultaneously for both receiving andtransmitting signals. The combination of received signal 4902 andtransmission signal 5026 is a duplexed signal 5028.

In the AM mode, the same circuit of FIG. 50 applies, except: (1) aninformation signal 5030 replaces information signal 5004; (2)bias/reference signal 5006 is a function of the information signal 5030;and (3) oscillating signal 5002 is not modulated.

This description is for the full-duplex mode of the transceiver whereinthe transmitting portion of the communications system is a separatecircuit than the receiver portion. A possible embodiment of ahalf-duplex mode is described below.

Alternate embodiments of the transceiver are possible. For example,FIGS. 51A through. 51D illustrate an embodiment of the transceiverwherein it may be desired, for cost or other considerations, for anoscillator to be shared by both the transmitter portion and the receiverportion of the circuit. To do this, a trade off must be made inselecting the frequency of the oscillator. In FIG. 51A, a localoscillator 5104 generates an oscillating signal 5106 which is mixed withsignal 4911 to generate a first IF signal 5108. A local oscillator 5110generates a second oscillating signal 5112 which is mixed with the firstIF signal 5108 to generate a second IF signal 5114. For the exampleherein, the frequencies of the oscillating signals 5106 and 5112 will belower than the frequencies of signal 4911 and first IF signal 5108,respectively. (One skilled in the relevant art(s) will recognize that,because the mixers 4912 and 4922 create both the sum and the differenceof the signals they receive, the oscillator frequencies could be higherthan the signal frequencies.)

As described in the example above, a typical second IF frequency is 11MHz. The selection of this IF frequency is less flexible than is theselection of the first IF frequency, since the second IF frequency isrouted to a decoder where the signal is demodulated and decoded.Typically, demodulators and decoders are designed to receive signals ata predetermined, fixed frequency, e.g., 11 MHz. If this is the case, thecombination of the first IF signal 5108 and the second oscillatingsignal 5112 must generate a second IF signal with a second IF frequencyof 111 MHz. Recall that the received signal 4902 was 900 MHz in theexample above. To achieve the second IF signal frequency of 11 MHz, thefrequencies of the oscillating signals 4916 and 4926 were set at 830 MHzand 59 MHz. Before setting the frequencies of the oscillating signals5106 and 5112, the desired frequency of the transmitted signal must bedetermined. If it, too, is 900 MHz, then the frequency of theoscillating signal that causes the switch in the present invention toopen and close must be a “sub-harmonic” of 900 MHz. That is, it must bethe quotient of 900 MHz divided by an integer. (In other words, 900 MHzmust be a harmonic of the oscillating signal that drives the switch.)The table below is a list of some of the sub-harmonics of 900 MHz:sub-harmonic frequency  1^(st) 900 MHz  2^(nd) 450  3^(rd) 300  4^(th)225  5^(th) 180 10^(th)  90 15^(th)  60

Recall that the frequency of the second oscillating signal 4926 in FIGS.49 and 50 was 59 MHz. Notice that the frequency of the 15^(th)sub-harmonic is 60 MHz. If the frequency of oscillating signal 5112 ofFIG. 51 were set at 60 MHz, it could also be used as the oscillatingsignal to operate the switches in switch module 5126 of FIG. 51B andswitch module 5136 of FIG. 51C. If this were done, the frequency of thefirst IF signal would be 71 MHz (rather than 70 MHz in the previousexample of a stand-alone receiver), as indicated below: $\begin{matrix}{{{First}\quad{IF}\quad{frequency}} = {{{Second}\quad{IF}\quad{frequency}} +}} \\{{Second}\quad{oscillating}\quad{frequency}} \\{= {{11\quad{MHz}} + {60\quad{MHz}}}} \\{= {71\quad{MHz}}}\end{matrix}$

The frequency of the first oscillating signal 5106 can be determinedfrom the values of the first IF frequency and the frequency of thereceived signal 4902. In this example, the frequency of the receivedsignal is 900 MHz and the frequency of the first IF signal is 71 MHz.Therefore, the frequency of the first oscillating signal 5106 must be829 MHz, as indicated below: $\begin{matrix}{{{First}\quad{oscillating}\quad{frequency}} = {{{Freq}\quad{of}\quad{received}\quad{signal}} -}} \\{{First}\quad{IF}\quad{freq}} \\{= {{900\quad{MHz}} - {71\quad{MHz}}}} \\{= {829\quad{MHz}}}\end{matrix}$

Thus the frequencies of the oscillating signals 5106 and 5112 are 829MHz and 60 MHz, respectively.

In FIG. 51B, the PM embodiment is shown. The second oscillating signal5112 is routed to a phase modulator 5122 where it is modulated by theinformation signal 5120 to generate a PM signal 5132. PM signal 5132 isrouted to a harmonic enhancement module 5124 to create a string ofpulses 5133. The string of pulses 5133 is also a phase modulated signaland is used to cause the switch in switch module 5126 to open and close.Also entering switch module 5126 is a bias signal 5128. The output ofswitch module 5126 is a harmonically rich signal 5134.

In FIG. 51C, the AM embodiment is shown. The second oscillating signal5112 directly enters the harmonic enhancement module 5124 to create astring of pulses 5138. String of pulses 5138 (not modulated in thisembodiment) then enters a switch module 5136 where it causes a switch toopen and close. Also entering switch module 5136 is a reference signal5140. Reference signal is created by summing module 5130 by combininginformation signal 5120 with bias signal 5128. It is well known to thoseskilled in the relevant art(s) that the information signal 5120 may beused as the reference signal without being combined with the bias signal5128. The output of switch module 5136 is a harmonically rich signal5134.

The scope of the invention includes an FM embodiment wherein theoscillator 5110 of the receiver circuit is used as a source for anoscillating signal for the transmitter circuit. In the embodimentsdiscussed above, the FM embodiment requires a voltage controlledoscillator (VCO) rather than a simple local oscillator. There arecircuit designs that would be apparent to those skilled in the relevantart(s) based on the discussion contained herein, wherein a VCO is usedin place of a local oscillator in the receiver circuit.

In FIG. 51D, the harmonically rich signal 5134 is filtered by a filter5142, which removes all but the desired output frequency 5148. Thedesired output frequency 5148 is amplified by amplifier module 5146 androuted to transmission module 5150. The output of transmission module5150 is a transmission signal 5144. Transmission signal 5144 is thenrouted to the antenna 4904 for transmission.

Those skilled in the relevant art(s) will understand that there arenumerous combinations of oscillator frequencies, stages, and circuitsthat will meet the scope and intent of this invention. Thus, thedescription included herein is for illustrative purposes only and notmeant to be limiting.

6.2.2 Second Embodiment: The Transmitter of the Present Invention BeingUsed with a Universal Frequency Down-Converter in a Half-Duplex Mode.

An exemplary receiver using universal frequency down conversiontechniques is shown in FIG. 52 and described in section 6.3, below. Anantenna 5202 receives an electromagnetic (EM) signal 5220. EM signal5220 is routed through a capacitor 5204 to a first terminal of a switch5210. The other terminal of switch 5210 is connected to ground 5212 inthis exemplary embodiment. A local oscillator 5206 generates anoscillating signal 5228 which is routed through a pulse shaper 5208. Theresult is a string of pulses 5230. The selection of the oscillator 5206and the design of the pulse shaper 5208 control the frequency and pulsewidth of the string of pulses 5230. The string of pulses 5230 controlthe opening and closing of switch 5210. As a result of the opening andclosing of switch 5210, a down converted signal 5222 results. Downconverted signal 5222 is routed through an amplifier 5214 and a filter5216, and a filtered signal 5224 results. In a preferred embodiment,filtered signal 5224 is at baseband, and a decoder 5218 may only beneeded to convert digital to analog or to remove encryption beforeoutputting the baseband information signal. This then is a universalfrequency down conversion receiver operating in a direct down conversionmode, in that it receives the EM signal 5220 and down converts it tobaseband signal 5226 without requiring an IF or a demodulator. In analternate embodiment, the filtered signal 5224 may be at an “offset”frequency. That is, it is at an intermediate frequency, similar to thatdescribed above for the second IF signal in a typical superheterodynereceiver. In this case, the decoder 5218 would be used to demodulate thefiltered signal so that it could output a baseband signal 5226.

An exemplary transmitter using the present invention is shown in FIG.53. In the FM and PM embodiments, an information signal 5302 modulatesan oscillating signal 5306 which is routed to a pulse shaping circuit5310 which outputs a string of pulses 5311. The string of pulses 5311controls the opening and closing of the switch 5312. One terminal ofswitch 5312 is connected to ground 5314, and the second terminal ofswitch 5312 is connected through a resistor 5330 to a bias/referencesignal 5308. In the FM and PM modes, bias/reference signal 5308 ispreferably a non-varying signal, often referred to simply as the biassignal. In the AM mode, the oscillating signal 5306 is not modulated,and the bias/reference signal is a function of the information signal5304. In one embodiment, information signal 5304 is combined with a biasvoltage to generate the reference signal 5308. In an alternateembodiment, the information signal 5304 is used without being combinedwith a bias voltage. Typically, in the AM mode, this bias/referencesignal is referred to as the reference signal to distinguish it from thebias signal used in the FM and PM modes. The output of switch 5312 is aharmonically rich signal 5316 which is routed to a “high Q” filter whichremoves the unwanted frequencies that exist as harmonic components ofharmonically rich signal 5316. Desired frequency 5320 is amplified byamplifier module 5322 and routed to transmission module 5324 whichoutputs a transmission signal 5326. Transmission signal is output byantenna 5328 in this embodiment.

For the FM and PM modulation modes, FIGS. 54A, 54B, and 54C show thecombination of the present invention of the transmitter and theuniversal frequency down-conversion receiver in the half-duplex modeaccording to an embodiment of the invention. That is, the transceivercan transmit and receive, but it cannot do both simultaneously. It usesa single antenna 5402, a single oscillator 5444/5454 (depending onwhether the transmitter is in the FM or PM modulation mode), a singlepulse shaper 5438, and a single switch 5420 to transmit and to receive.In the receive function, “Receiver/Transmitter” (R/T) switches 5406,5408, and 5446/5452 (FM or PM) would all be in the receive position,designated by (R). The antenna 5402 receives an EM signal 5404 androutes it through a capacitor 5407. In the FM modulation mode,oscillating signal 5436 is generated by a voltage controlled oscillator(VCO) 5444. Because the transceiver is performing the receive function,switch 5446 connects the input to the VCO 5444 to ground 5448. Thus, VCO5444 will operate as if it were a simple oscillator. In the PMmodulation mode, oscillating signal 5436 is generated by localoscillator 5454 which is routed through phase modulator 5456. Since thetransceiver is performing the receive function, switch 5452 is connectedto ground 5448, and there is no modulating input to phase modulator.Thus, local oscillator 5454 and phase modulator 5456 operate as if theywere a simple oscillator. One skilled in the relevant art(s) willrecognize based on the discussion contained herein that there arenumerous embodiments wherein an oscillating signal 5436 can be generatedto control the switch 5420.

Oscillating signal 5436 is shaped by pulse shaper 5438 to produce astring of pulses 5440. The string of pulses 5440 cause the switch 5420to open and close. As a result of the switch opening and closing, a downconverted signal 5409 is generated. The down converted signal 5409 isamplified and filtered to create a filtered signal 5413. In anembodiment, filtered signal 5413 is at baseband and, as a result of thedown conversion, is demodulated. Thus, a decoder 5414 may not berequired except to convert digital to analog or to decrypt the filteredsignal 5413. In an alternate embodiment, the filtered signal 5413 is atan “offset” frequency, so that the decoder 5414 is needed to demodulatethe filtered signal and create a demodulated baseband signal.

When the transceiver is performing the transmit function, the R/Tswitches 5406, 5408, and 5446/5452 (FM or PM) are in the (T) position.In the FM modulation mode, an information signal 5450 is connected byswitch 5446 to VCO 5444 to create a frequency modulated oscillatingsignal 5436. In the PM modulation mode switch 5452 connects informationsignal 5450 to the phase modulator 5456 to create a phase modulatedoscillating signal 5436. Oscillation signal 5436 is routed through pulseshaper 5438 to create a string of pulses 5440 which in turn cause switch5420 to open and close. One terminal of switch 5420 is connected toground 5442 and the other is connected through switch R/T 5408 andresistor 5423 to a bias signal 5422. The result is a harmonically richsignal 5424 which is routed to a “high Q” filter 5426 which removes theunwanted frequencies that exist as harmonic components of harmonicallyrich signal 5424. Desired frequency 5428 is amplified by amplifiermodule 5430 and routed to transmission module 5432 which outputs atransmission signal 5434. Again, because the transceiver is performingthe transmit function, τ/T switch 5406 connects the transmission signalto the antenna 5402.

In the AM modulation mode, the transceiver operates in the half duplexmode as shown in FIG. 55. The only distinction between this modulationmode and the FM and PM modulation modes described above, is that theoscillating signal 5436 is generated by a local oscillator 5502, and theswitch 5420 is connected through the τ/T switch 5408 and resistor 5423to a reference signal 5506. Reference signal 5506 is generated wheninformation signal 5450 and bias signal 5422 are combined by a summingmodule 5504. It is well known to those skilled in the relevant art(s)that the information signal 5450 may be used as the reference signal5506 without being combined with the bias signal 5422, and may beconnected directly (through resistor 5423 and τ/T switch 5408) to theswitch 5420.

6.2.3 Third Embodiment: The Transmitter of the Present Invention BeingUsed with a Universal Frequency Down Converter in a Full-Duplex Mode.

The full-duplex mode differs from the half-duplex mode in that thetransceiver can transmit and receive simultaneously. Referring to FIG.56, to achieve this, the transceiver preferably uses a separate circuitfor each function. A duplexer 5604 is used in the transceiver to permitthe sharing of an antenna 5602 for both the transmit and receivefunctions.

The receiver function performs as follows. The antenna 5602 receives anEM signal 5606 and routes it through a capacitor 5607 to one terminal ofa switch 5626. The other terminal of switch 5626 is connected to ground5628, and the switch is driven as a result of a string of pulses 5624created by local oscillator 5620 and pulse shaper 5622. The opening andclosing of switch 5626 generates a down converted signal 5614. Downconverted signal 5614 is routed through a amplifier 5608 and a filter5610 to generate filtered signal 5616. Filtered signal 5616 may be atbaseband and be demodulated or it may be at an “offset” frequency. Iffiltered signal 5616 is at an offset frequency, decoder 5612 willdemodulate it to create the demodulated baseband signal 5618. In apreferred embodiment, however, the filtered signal 5616 will be ademodulated baseband signal, and decoder 5612 may not be required exceptto convert digital to analog or to decrypt filtered signal 5616. Thisreceiver portion of the transceiver can operate independently from thetransmitter portion of the transceiver.

The transmitter function is performed as follows. In the FM and PMmodulation modes, an information signal 5648 modulates an oscillatingsignal 5630. In the AM modulation mode, the oscillating signal 5630 isnot modulated. The oscillating signal is shaped by pulse shaper 5632 anda string of pulses 5634 is created. This string of pulses 5634 causes aswitch 5636 to open and close. One terminal of switch 5636 is connectedto ground 5638, and the other terminal is connected through a resistor5647 to a bias/reference signal 5646. In the FM and PM modulation modes,bias/reference signal 5646 is referred to as a bias signal 5646, and itis substantially non-varying. In the AM modulation mode, an informationsignal 5650 may be combined with the bias signal to create what isreferred to as the reference signal 5646. The reference signal 5646 is afunction of the information signal 5650. It is well known to thoseskilled in the relevant art(s) that the information signal 5650 may beused as the bias/reference signal 5646 directly without being summedwith a bias signal. A harmonically rich signal 5652 is generated and isfiltered by a “high Q” filter 5640, thereby producing a desired signal5654. The desired signal 5654 is amplified by amplifier 5642 and routedto transmission module 5644. The output of transmission module 5644 istransmission signal 5656. Transmission signal 5656 is routed to duplexer5604 and then transmitted by antenna 5602. This transmitter portion ofthe transceiver can operate independently from the receiver portion ofthe transceiver.

Thus, as described above, the transceiver embodiment the presentinvention as shown in FIG. 56 can perform full-duplex communications inall modulation modes.

6.2.4 Other Embodiments and Implementations.

Other embodiments and implementations of the receiver/transmitter of thepresent invention would be apparent to one skilled in the relevantart(s) based on the discussion herein.

The embodiments and implementations described above are provided forpurposes of illustration. These embodiments and implementations are notintended to limit the invention. Alternatives, differing slightly orsubstantially from those described herein, will be apparent to personsskilled in the relevant art(s) based on the teachings contained herein.Such alternate embodiments and implementations fall within the scope andspirit of the present invention.

6.3 Summary Description of Down-conversion Using a Universal FrequencyTranslation Module.

The following discussion describes down-converting using a UniversalFrequency Translation Module. The down-conversion of an EM signal byaliasing the EM signal at an aliasing rate is fully described inco-pending U.S. patent application entitled “Method and System forDown-Converting Electromagnetic Signals,” Ser. No. 09/176,022, filedOct. 21, 1998, the full disclosure of which is incorporated herein byreference. A relevant portion of the above mentioned patent applicationis summarized below to describe down-converting an input signal toproduce a down-converted signal that exists at a lower frequency or abaseband signal.

FIG. 64A illustrates an aliasing module 6400 for down-conversion using auniversal frequency translation (UFT) module 6402 which down-converts anEM input signal 6404. In particular embodiments, aliasing module 6400includes a switch 6408 and a capacitor 6410. The electronic alignment ofthe circuit components is flexible. That is, in one implementation, theswitch 6408 is in series with input signal 6404 and capacitor 6410 isshunted to ground (although it may be other than ground inconfigurations such as differential mode). In a second implementation(see FIG. 64A-1), the capacitor 6410 is in series with the input signal6404 and the switch 6408 is shunted to ground (although it may be otherthan ground in configurations such as differential mode). Aliasingmodule 6400 with UFT module 6402 can be easily tailored to down-converta wide variety of electromagnetic signals using aliasing frequenciesthat are well below the frequencies of the EM input signal 6404.

In one implementation, aliasing module 6400 down-converts the inputsignal 6404 to an intermediate frequency (IF) signal. In anotherimplementation, the aliasing module 6400 down-converts the input signal6404 to a demodulated baseband signal. In yet another implementation,the input signal 6404 is a frequency modulated (FM) signal, and thealiasing module 6400 down-converts it to a non-FM signal, such as aphase modulated (PM) signal or an amplitude modulated (AM) signal. Eachof the above implementations is described below.

In an embodiment, the control signal 6406 includes a train of pulsesthat repeat at an aliasing rate that is equal to, or less than, twicethe frequency of the input signal 6404 In this embodiment, the controlsignal 6406 is referred to herein as an aliasing signal because it isbelow the Nyquist rate for the frequency of the input signal 6404.Preferably, the frequency of control signal 6406 is much less than theinput signal 6404.

The train of pulses 6418 as shown in FIG. 64D controls the switch 6408to alias the input signal 6404 with the control signal 6406 to generatea down-converted output signal 6412. More specifically, in anembodiment, switch 6408 closes on a first edge of each pulse 6420 ofFIG. 64D and opens on a second edge of each pulse. When the switch 6408is closed, the input signal 6404 is coupled to the capacitor 6410, andcharge is transferred from the input signal to the capacitor 6410. Thecharge stored during successive pulses forms down-converted outputsignal 6412.

Exemplary waveforms are shown in FIGS. 64B-64F.

FIG. 64B illustrates an analog amplitude modulated (AM) carrier signal6414 that is an example of input signal 6404. For illustrative purposes,in FIG. 64C, an analog AM carrier signal portion 6416 illustrates aportion of the analog AM carrier signal 6414 on an expanded time scale.The analog AM carrier signal portion 6416 illustrates the analog AMcarrier signal 6414 from time t_(0 to time t) ₁.

FIG. 64D illustrates an exemplary aliasing signal 6418 that is anexample of control signal 6406. Aliasing signal 6418 is on approximatelythe same time scale as the analog AM carrier signal portion 6416. In theexample shown in FIG. 64D, the aliasing signal 6418 includes a train ofpulses 6420 having negligible apertures that tend towards zero (theinvention is not limited to this embodiment, as discussed below). Thepulse aperture may also be referred to as the pulse width as will beunderstood by those skilled in the art(s). The pulses 6420 repeat at analiasing rate, or pulse repetition rate of aliasing signal 6418. Thealiasing rate is determined as described below, and further described inco-pending U.S. patent application entitled “Method and System forDown-Converting Electromagnetic Signals,” Ser. No. 09/176,022, filedOct. 21, 1998.

As noted above, the train of pulses 6420 (i.e., control signal 6406)control the switch 6408 to alias the analog AM carrier signal 6416(i.e., input signal 6404) at the aliasing rate of the aliasing signal6418. Specifically, in this embodiment, the switch 6408 closes on afirst edge of each pulse and opens on a second edge of each pulse. Whenthe switch 6408 is closed, input signal 6404 is coupled to the capacitor6410, and charge is transferred from the input signal 6404 to thecapacitor 6410. The charge transferred during a pulse is referred toherein as an under-sample. Exemplary under-samples 6422 formdown-converted signal portion 6424 (FIG. 64E) that corresponds to theanalog AM carrier signal portion 6416 (FIG. 64C) and the train of pulses6420 (FIG. 64D). The charge stored during successive under-samples of AMcarrier signal 6414 form the down-converted signal 6424 (FIG. 64E) thatis an example of down-converted output signal 6412 (FIG. 64A). In FIG.64F a demodulated baseband signal 6426 represents the demodulatedbaseband signal 6424 after filtering on a compressed time scale. Asillustrated, down-converted signal 6426 has substantially the same“amplitude envelope” as AM carrier signal 6414. Therefore, FIGS. 64B-64Fillustrate down-conversion of AM carrier signal 6414.

The waveforms shown in FIGS. 64B-64F are discussed herein forillustrative purposes only, and are not limiting. Additional exemplarytime domain and frequency domain drawings, and exemplary methods andsystems of the invention relating thereto, are disclosed in co-pendingU.S. patent application entitled “Method and System for Down-ConvertingElectromagnetic Signals,” Ser. No. 09/176,022, filed Oct. 21, 1998.

The aliasing rate of control signal 6406 determines whether the inputsignal 6404 is down-converted to an IF signal, down-converted to ademodulated baseband signal, or down-converted from an FM signal to a PMor an AM signal. Generally, relationships between the input signal 6404,the aliasing rate of the control signal 6406, and the down-convertedoutput signal 6412 are illustrated below:(Freq. of input signal 6404)=n·(Freq. of control signal 6406)±(Freq. ofdown-converted output signal 6412)For the examples contained herein, only the “+” condition will bediscussed. The value of n represents a harmonic or sub-harmonic of inputsignal 6404 (e.g., n=0.5, 1, 2, 3, . . . ).

When the aliasing rate of control signal 6406 is off-set from thefrequency of input signal 6404, or off-set from a harmonic orsub-harmonic thereof, input signal 6404 is down-converted to an IFsignal. This is because the under-sampling pulses occur at differentphases of subsequent cycles of input signal 6404. As a result, theunder-samples form a lower frequency oscillating pattern. If the inputsignal 6404 includes lower frequency changes, such as amplitude,frequency, phase, etc., or any combination thereof, the charge storedduring associated under-samples reflects the lower frequency changes,resulting in similar changes on the down-converted IF signal. Forexample, to down-convert a 901 MHz input signal to a 1 MHz IF signal,the frequency of the control signal 6406 would be calculated as follows:(Freq _(input) −Freq _(IF))/n=Freq _(control)(900 MHz−1 MHz)/n=900 MHz/nFor n=0.5, 1, 2, 3, 4, etc., the frequency of the control signal 6406would be substantially equal to 1.8 GHz, 900 MHz, 450 MHz, 300 MHz, 225MHz, etc.

Exemplary time domain and frequency domain drawings, illustratingdown-conversion of analog and digital AM, PM and FM signals to IFsignal, and exemplary methods and systems thereof, are disclosed inco-pending U.S. patent application entitled “Method and System forDown-Converting Electromagnetic Signals,” Ser. No. 09/176,022, filedOct. 21, 1998.

Alternatively, when the aliasing rate of the control signal 6406 issubstantially equal to the frequency of the input signal 6404, orsubstantially equal to a harmonic or sub-harmonic thereof, input signal6404 is directly down-converted to a demodulated baseband signal. Thisis because, without modulation, the under-sampling pulses occur at thesame point of subsequent cycles of the input signal 6404. As a result,the under-samples form a constant output baseband signal. If the inputsignal 6404 includes lower frequency changes, such as amplitude,frequency, phase, etc., or any combination thereof, the charge storedduring associated under-samples reflects the lower frequency changes,resulting in similar changes on the demodulated baseband signal. Forexample, to directly down-convert a 900 MHz input signal to ademodulated baseband signal (i.e., zero IF), the frequency of thecontrol signal 6406 would be calculated as follows:(Freq _(input) −Freq _(IF))/n=Freq _(control)(900 MHz−0 MHz)/n=900 MHz/nFor n=0.5, 1, 2, 3, 4, etc., the frequency of the control signal 6406should be substantially equal to 1.8 GHz, 900 MHz, 450 MHz, 300 MHz, 225MHz, etc.

Exemplary time domain and frequency domain drawings, illustrating directdown-conversion of analog and digital AM and PM signals to demodulatedbaseband signals, and exemplary methods and systems thereof, aredisclosed in the co-pending U.S. patent application entitled “Method andSystem for Down-Converting Electromagnetic Signals,” Ser. No.09/176,022, filed Oct. 21, 1998.

Alternatively, to down-convert an input FM signal to a non-FM signal, afrequency within the FM bandwidth must be down-converted to baseband(i.e., zero IF). As an example, to down-convert a frequency shift keying(FSK) signal (a sub-set of FM) to a phase shift keying (PSK) signal (asubset of PM), the mid-point between a lower frequency F₁ and an upperfrequency F₂ (that is, [(F₁+F₂)÷2]) of the FSK signal is down-convertedto zero IF. For example, to down-convert an FSK signal having F₁ equalto 899 MHz and F₂ equal to 901 MHz, to a PSK signal, the aliasing rateof the control signal 6406 would be calculated as follows:$\begin{matrix}{{{Frequency}\quad{of}\quad{the}\quad{input}} = {( {F_{1} + F_{2}} ) \div 2}} \\{= {( {{899\quad{MHz}} + {901\quad{MHz}}} ) \div 2}} \\{= {900\quad{MHz}}}\end{matrix}$

Frequency of the down-converted signal=0 (i.e., baseband)(Freq _(input) −Freq _(IF))/n=Freq _(control)(900 MHz−0 MHz)/n=900 MHz/nFor n=0.5, 1, 2, 3, etc., the frequency of the control signal 6406should be substantially equal to 1.8 GHz, 900 MHz, 450 MHz, 300 MHz, 225MHz, etc. The frequency of the down-converted PSK signal issubstantially equal to one half the difference between the lowerfrequency F₁ and the upper frequency F₂.

As another example, to down-convert a FSK signal to an amplitude shiftkeying (ASK) signal (a subset of AM), either the lower frequency F₁ orthe upper frequency F₂ of the FSK signal is down-converted to zero IF.For example, to down-convert an FSK signal having F₁ equal to 900 MHzand F₂ equal to 901 MHz, to an ASK signal, the aliasing rate of thecontrol signal 6406 should be substantially equal to:

-   -   (900 MHz−0 MHz)/n=900 MHz/n, or    -   (901 MHz−0 MHz)/n=901 MHz/n.        For the former case of 900 MHz/n, and for n=0.5, 1, 2, 3, 4,        etc., the frequency of the control signal 6406 should be        substantially equal to 1.8 GHz, 900 MHz, 450 MHz, 300 MHz, 225        MHz, etc. For the latter case of 901 MHz/n, and for n=0.5, 1, 2,        3, 4, etc., the frequency of the control signal 6406 should be        substantially equal to 1.802 GHz, 901 MHz, 450.5 MHz, 300.333        MHz, 225.25 MHz, etc. The frequency of the down-converted AM        signal is substantially equal to the difference between the        lower frequency F₁ and the upper frequency F₂ (i.e., 1 MHz).

Exemplary time domain and frequency domain drawings, illustratingdown-conversion of FM signals to non-FM signals, and exemplary methodsand systems thereof, are disclosed in the co-pending U.S. patentapplication entitled “Method and System for Down-ConvertingElectromagnetic Signals,” Ser. No. 09/176,022, filed Oct. 21, 1998.

In an embodiment, the pulses of the control signal 6406 have negligibleapertures that tend towards zero. This makes the UFT module 6402 a highinput impedance device. This configuration is useful for situationswhere minimal disturbance of the input signal may be desired.

In another embodiment, the pulses of the control signal 6406 havenon-negligible apertures that tend away from zero. This makes the UFTmodule 6402 a lower input impedance device. This allows the lower inputimpedance of the UFT module 6402 to be substantially matched with asource impedance of the input signal 6404. This also improves the energytransfer from the input signal 6404 to the down-converted output signal6412, and hence the efficiency and signal to noise (s/n) ratio of UFTmodule 6402.

Exemplary systems and methods for generating and optimizing the controlsignal 6406, and for otherwise improving energy transfer and s/n ratio,are disclosed in the co-pending U.S. patent application entitled “Methodand System for Down-Converting Electromagnetic Signals,” Ser. No.09/176,022, filed Oct. 21, 1998.

7. Designing a Transmitter According to an Embodiment of the PresentInvention.

This section (including its subsections) provides a high-leveldescription of an exemplary process to be used to design a transmitteraccording to an embodiment of the present invention. The techniquesdescribed herein are also applicable to designing a frequencyup-converter for any application, and for designing the applicationsthemselves. The descriptions are contained herein for illustrativepurposes and are not limiting. Alternatives (including equivalents,extensions, variations, deviations, etc., of those described herein)will be apparent to persons skilled in the relevant art(s) based on theteachings contained herein. Such alternatives fall within the scope andspirit of the present invention, and the invention is intended andadapted to include such alternative.

The discussion herein describes an exemplary process to be used todesign a transmitter according to an embodiment of the presentinvention. An exemplary circuit for a transmitter of the presentinvention operating in the FM embodiment is shown in FIG. 57A. Likewise,FIG. 57B illustrates the transmitter of the present invention operatingin the PM embodiment, and FIG. 57C shows the transmitter of the presentinvention operating in the AM embodiment. These circuits have been shownin previous figures, but are presented here to facilitate the discussionof the design. As the “I/Q” embodiment of the present invention is asubset of the PM embodiment, it will not be shown in a separate figurehere, since the design approach will be very similar to that for the PMembodiment.

Depending on the application and on the implementation, some of thedesign considerations may not apply. For example, and withoutlimitation, in some cases it may not be necessary to optimize the pulsewidth or to include an amplifier.

7.1 Frequency of the Transmission Signal.

The first step in the design process is to determine the frequency ofthe desired transmission signal 5714. This is typically determined bythe application for which the transmitter is to be used. The presentinvention is for a transmitter that can be used for all frequencieswithin the electromagnetic (EM) spectrum. For the examples herein, theexplanation will focus on the use of the transmitter in the 900 MHz to950 MHz range. Those skilled in the relevant art(s) will recognize thatthe analysis contained herein may be used for any frequency or frequencyrange.

7.2 Characteristics of the Transmission Signal

Once the frequency of the desired transmission signal 5714 is known, thecharacteristics of the signal must be determined. These characteristicsinclude, but are not limited to, whether the transmitter will operate ata fixed frequency or over a range of frequencies, and if it is tooperate over a range of frequencies, whether those frequencies arecontinuous or are divided into discrete “channels.” If the frequencyrange is divided into discrete channels, the spacing between thechannels must be ascertained. As an example, cordless phones operatingin this frequency range may operate on discrete channels that are 50 KHzapart. That is, if the cordless phones operate in the 905 MHz to 915 MHzrange (inclusive), the channels could be found at 905.000, 905.050,905.100, . . . , 914.900, 914.950, and 915.000.

7.3 Modulation Scheme.

Another characteristic that must be ascertained is the desiredmodulation scheme that is to be used. As described above in sections2.1-2.2.4, above, these modulation schemes include FM, PM, AM, etc., andany combination or subset thereof, specifically including the widelyused “I/Q” subset of PM. Just as the frequency of the desiredtransmission signal 5714 is typically determined by the intendedapplication, so too is the modulation scheme.

7.4 Characteristics of the Information Signal.

The characteristics of an information signal 5702 are also factors inthe design of the transmitter circuit. Specifically, the bandwidth ofthe information signal 5702 defines the minimum frequency for anoscillating signal 5704, 5738, 5744 (for the FM, PM, and AM modes,respectively).

7.5 Characteristics of the Oscillating Signal.

The desired frequency of the oscillating signal 5704, 5738, 5744 is alsoa function of the frequency and characteristics of the desiredtransmission signal 5714. Also, the frequency and characteristics of thedesired transmission signal 5714 are factors in determining the pulsewidth of the pulses in a string of pulses 5706. Note that the frequencyof the oscillating signal 5704, 5738, 5744 is substantially the same asthe frequency of the string of pulses 5706. (An exception, which isdiscussed below, is when a pulse shaping circuit 5722 increases thefrequency of the oscillating signal 5704, 5738, 5744 in a manner similarto that described above in section 4.3.2.) Note also that the frequencyand pulse width of the string of pulses 5706 is substantially the sameas the frequency and pulse width of a harmonically rich signal 5708.

7.5.1 Frequency of the Oscillating Signal.

The frequency of the oscillating signal 5704, 5738, 5744 must be asubharmonic of the frequency of the desired transmission signal 5714. Asubharmonic is the quotient obtained by dividing the fundamentalfrequency, in this case the frequency of the desired transmission signal5714, by an integer. When describing the frequency of certain signals,reference is often made herein to a specific value. It is understood bythose skilled in the relevant art(s) that this reference is to thenominal center frequency of the signal, and that the actual signal mayvary in frequency above and below this nominal center frequency based onthe desired modulation technique being used in the circuit. As anexample to be used herein, if the frequency of the desired transmissionsignal is 910 MHz, and it is to be used in an FM mode where, forexample, the frequency range of the modulation is 40 KHz, the actualfrequency of the signal will vary ±20 KHz around the nominal centerfrequency as a function of the information being transmitted. That is,the frequency of the desired transmission signal will actually rangebetween 909.980 MHz and 910.020 MHz.

The first ten subharmonics of a 910.000 MHz signal are given below.harmonic frequency  1^(st) 910.000 MHz  2^(nd) 455.000  3^(rd) 303.333 .. .  4^(th) 227.500  5^(th) 182.000  6^(th) 151.666 . . .  7^(th)130.000  8^(th) 113.750  9^(th) 101.111 . . . 10^(th)  91.000

The oscillating signal 5704, 5738, 5744 can be at any one of thesefrequencies or, if desired, at a lower subharmonic. For discussionherein, the 9^(th) subharmonic will be chosen. Those skilled in therelevant art(s) will understand that the analysis herein appliesregardless of which harmonic is chosen. Thus the nominal centerfrequency of the oscillating signal 5704, 5738, 5744 will be 101.1111MHz. Recalling that in the FM mode, the frequency of the desiredtransmission signal 5714 is actually 910.000 MHz±0.020 MHz, it can beshown that the frequency of the oscillating signal 5704 will vary±0.00222 MHz (i.e., from 101.10889 MHz to 101.11333 MHz). The frequencyand frequency sensitivity of the oscillating signal 5704 will drive theselection or design of the voltage controlled oscillator (VCO) 5720.

Another frequency consideration is the overall frequency range of thedesired transmission signal. That is, if the transmitter is to be usedin the cordless phone of the above example and will transmit on allchannels between 905 MHz and 915 MHz, the VCO 5720 (for the FM mode) orthe local oscillator (LO) 5734 (for the PM and AM modes) will berequired to generate oscillating frequencies 5704, 5738, 5744 that rangefrom 100.5556 MHz to 101.6667 MHz. (That is, the 9^(th) subharmonic of910 MHz±5 MHz). In some applications, such as the cellular phone, thefrequencies will change automatically, based on the protocols of theoverall cellular system (e.g., moving from one cell to an adjacentcell). In other applications, such as a police radio, the frequencieswill change based on the user changing channels.

In some applications, different models of the same transmitter willtransmit signals at different frequencies, but each model will, itself,only transmit a single frequency. A possible example of this might beremote controlled toy cars, where each toy car operates on its ownfrequency, but, in order for several toy cars to operate in the samearea, there are several frequencies at which they could operate. Thus,the design of the VCO 5720 or LO 5734 will be such that it is able to betuned to a set frequency when the circuit is fabricated, but the userwill typically not be able to adjust the frequency.

It is well known to those skilled in the relevant art(s) that several ofthe criteria to be considered in the selection or design of anoscillator (VCO 5720 or LO 5734) include, but are not limited to, thenominal center frequency of the desired transmission signal 5714, thefrequency sensitivity caused by the desired modulation scheme, the rangeof all possible frequencies for the desired transmission signal 5714,and the tuning requirements for each specific application. Anotherimportant criterion is the determination of the subharmonic to be used,but unlike the criteria listed above which are dependent on the desiredapplication, there is some flexibility in the selection of thesubharmonic.

7.5.2 Pulse Width of the String of Pulses.

Once the frequency of the oscillating signal 5704, 5738, 5744 has beenselected, the pulse width of the pulses in the stream of pulses 5706must be determined. (See sections 4-4.3.4, above, for a discussion ofharmonic enhancement and the impact the pulse-width-to-period ratio hason the relative amplitudes of the harmonics in a harmonically richsignal 5708.) In the example used above, the 9^(th) subharmonic wasselected as the frequency of the oscillating signal 5704, 5738, 5744. Inother words, the frequency of the desired transmission signal will bethe 9^(th) harmonic of the oscillating signal 5704, 5738, 5744. Oneapproach in selecting the pulse width might be to focus entirely on thefrequency of the oscillating signal 5704, 5738, 5744 and select a pulsewidth and observe its operation in the circuit. For the case where theharmonically rich signal 5708 has a unity amplitude, and thepulse-width-to-period ratio is 0.1, the amplitude of the 9^(th) harmonicwill be 0.0219. Looking again at Table 6000 and FIG. 58 it can be seenthat the amplitude of the 9^(th) harmonic is higher than that of the10^(th) harmonic (which is zero) but is less than half the amplitude ofthe 8^(th) harmonic. Because the 9^(th) harmonic does have an amplitude,this pulse-width-to-period ratio could be used with proper filtering.Typically, a different ratio might be selected to try and find a ratiothat would provide a higher amplitude.

Looking at Eq. 1 in section 4.1.1, it is seen that the relativeamplitude of any harmonic is a function of the number of the harmonicand the pulse-width-to-period ratio of the underlying waveform. Applyingcalculus of variations to the equation, the pulse-width-to-period ratiothat yields the highest amplitude harmonic for any given harmonic can bedetermined.

From Eq. 1, where A_(n) is the amplitude of the n^(th) harmonic,A _(n) =[A _(pulse)][(2/π)/n]sin{n·π·(τ/T)]  Eq. 2If the amplitude of the pulse, A_(pulse), is set to unity (i.e., equalto 1), the equation becomesA _(n)=[2/(n·π)]sin[n·π·(τ/T)]  Eq. 3From this equation, it can be seen that for any value of n (theharmonic) the amplitude of that harmonic, A_(n), is a function of thepulse-width-to-period ratio, τ/T. To determine the highest value ofA_(n) for a given value of n, the first derivative of A_(n) with respectto τ/T is taken. This gives the following equations. $\begin{matrix}{{{\delta( A_{n} )}/{\delta( {\tau/T} )}} = {\delta{\{ {\lbrack \frac{2}{( {n \cdot \pi} )} \rbrack{\sin\lbrack {n \cdot \pi \cdot ( \frac{\tau}{T} )} \rbrack}} \}/{\delta( \frac{\tau}{T} )}}}} & {{Eq}.\quad 4} \\{\quad{= {\lbrack \frac{2}{( {n \cdot \pi} )} \rbrack{\delta\lbrack {{\sin\lbrack {n \cdot \pi \cdot ( \frac{\tau}{T} )} \rbrack}/{\delta( \frac{\tau}{T} )}} }}}} & {{Eq}.\quad 5} \\{\quad{= {\lbrack \frac{2}{( {n \cdot \pi} )} \rbrack{\cos\lbrack {n \cdot \pi \cdot ( \frac{\tau}{T} )} \rbrack}}}} & {{Eq}.\quad 6}\end{matrix}$

From calculus of variations, it is known that when the first derivativeis set equal to zero, the value of the variable that will yield arelative maximum (or minimum) can be determined.δ(A _(n))/δ(τ/T)=0  Eq. 7[2/(n·π)]cos[n·π·(τ/T)]=0  Eq. 8cos[n·π·(τ/T)]=0  Eq. 9From trigonometry, it is known that for Eq. 9 to be true,n·π·(τ/T)=π/2 (or 3π/2, 5π/2, etc.)  Eq. 10τ/T=(π/2)/(n·π)  Eq. 11τ/T=1/(2·n) (or 3/(2·n), 5/(2·n), etc.)  Eq. 12The above derivation is well known to those skilled in the relevantart(s). From Eq. 12, it can be seen that if the pulse-width-to-periodratio is equal to 1/(2·n), the amplitude of the harmonic should besubstantially optimum. For the case of the 9^(th) harmonic, Eq. 12 willyield a pulse-width-to-period ratio of 1/(2·9) or 0.0556. For theamplitude of this 9^(th) harmonic, Table 6100 of FIG. 61 shows that itis 0.0796. This is an improvement over the previous amplitude for apulse-width-to-period ratio of 0.1. Table 6100 also shows that the9^(th) harmonic for this pulse-width-to-period ratio has the highestamplitude of any 9^(th) harmonic, which bears out the derivation above.The frequency spectrum for a pulse-width-to-period ratio of 0.0556 isshown in FIG. 59. (Note that other pulse-width-to-period ratios of3/(2·n), 5/(2·n), etc., will have amplitudes that are equal to but notlarger than this one.)

This is one approach to determining the desired pulse-width-to-periodratio: Those skilled in the relevant art(s) will understand that othertechniques may also be used to select a pulse-width-to-period ratio.

7.6 Design of the Pulse Shaping Circuit.

Once the determination has been made as to the desired frequency of theoscillating signal 5704, 5738, 5744 and of the pulse width, the pulseshaping circuit 5722 can be designed. Looking back to sections 4-4.3.4it can be seen that the pulse shaping circuit 5722 can not only producea pulse of a desired pulse width, but it can also cause the frequency ofthe string of pulses 5706 to be higher than the frequency of theoscillating signal 5704, 5738, 5744. Recall that thepulse-width-to-period ratio applies to the pulse-width-to-period ratioof the harmonically rich signal 5708 and not to thepulse-width-to-period ratio of the oscillating signal 5704, 5738, 5744,and that the frequency and pulse width of the harmonically rich signal5708 mirrors the frequency and pulse width of the string of pulses 5706.Thus, if in the selection of the VCO 5720 or LO 5734 it was desired tochoose an oscillator that is lower than that required for the selectedharmonic, the pulse shaping circuit 5733 can be used to increase thefrequency. Going back to the previous example, the frequency of theoscillating signal 5704, 5738, 5744 could be 50.5556 MHz rather than101.1111 MHz if the pulse shaping circuit 5722 was designed such asdiscussed in sections 4.2.2-4.2.2.2 (shown in FIGS. 40A-40D) not only toshape the pulse, but also to double the frequency. While that discussionwas specifically for a square wave input, those skilled in the relevantart(s) will understand that similar techniques will apply tonon-rectangular waveforms (e.g., a sinusoidal wave). This use of thepulse shaping circuit to double the frequency has a possible advantagein that it allows the design and selection of an oscillator (VCO 5720 ofLO 5734) with a lower frequency, if that is a consideration.

It should also be understood that the pulse shaping circuit 5722 is notalways required. If the design or selection of the VCO 5720 or LO 5734was such that the oscillating signal 5704, 5738, 5744 was asubstantially rectangular wave, and that substantially rectangular wavehad a pulse-width-to-period ratio that was adequate, the pulse shapingcircuit 5722 could be eliminated.

7.7 Selection of the Switch.

The selection of a switch 5724 can now be made. The switch 5724 is shownin the examples of FIGS. 57A, 57B, and 57C as a GaAsFET. However, it maybe any switching device of any technology that can open and close“crisply” enough to accommodate the frequency and pulse width of thestring of pulses 5706.

7.7.1 Optimized Switch Structures.

Switches of Different Sizes

In an embodiment, the switch modules discussed herein can be implementedas a series of switches operating in parallel as a single switch. Theseries of switches can be transistors, such as, for example, fieldeffect transistors (FET), bi-polar transistors, or any other suitablecircuit switching devices. The series of switches can be comprised ofone type of switching device, or a combination of different switchingdevices.

For example, FIG. 73 illustrates a switch module 7300. In FIG. 73, theswitch module is illustrated as a series of FETs 7302 a-n. The FETs 7302a-n can be any type of FET, including, but not limited to, a MOSFET, aJFET, a GaAsFET, etc. Each of FETs 7302 a-n includes a gate 7304 a-n, asource 7306 a-n, and a drain 7308 a-n. The series of FETs 7302 a-noperate in parallel. Gates 7304 a-n are coupled together, sources 7306a-n are coupled together, and drains 7308 a-n are coupled together. Eachof gates 7304 a-n receives the control signal 2804, 3104 to control theswitching action between corresponding sources 7306 a-n and drains 7308a-n. Generally, the corresponding sources 7306 a-n and drains 7308 a-nof each of FETs 7302 a-n are interchangeable. There is no numericallimit to the number of FETs. Any limitation would depend on theparticular application, and the “a-n” designation is not meant tosuggest a limit in any way.

In an embodiment, FETs 7302 a-n have similar characteristics. In anotherembodiment, one or more of FETs 7302 a-n have different characteristicsthan the other FETs. For example, FETs 7302 a-n may be of differentsizes. In CMOS, generally, the larger size a switch is (meaning thelarger the area under the gate between the source and drain regions),the longer it takes for the switch to turn on. The longer turn on timeis due in part to a higher gate to channel capacitance that exists inlarger switches. Smaller CMOS switches turn on in less time, but have ahigher channel resistance. Larger CMOS switches have lower channelresistance relative to smaller CMOS switches. Different turn oncharacteristics for different size switches provides flexibility indesigning an overall switch module structure. By combining smallerswitches with larger switches, the channel conductance of the overallswitch structure can be tailored to satisfy given requirements.

In an embodiment, FETs 7302 a-n are CMOS switches of different relativesizes. For example, FET 7302 a may be a switch with a smaller sizerelative to FETs 7302 b-n. FET 7302 b may be a switch with a larger sizerelative to FET 7302 a, but smaller size relative to FETs 7302 c-n. Thesizes of FETs 7302 c-n also may be varied relative to each other. Forinstance, progressively larger switch sizes may be used. By varying thesizes of FETs 7302 a-n relative to each other, the turn oncharacteristic curve of the switch module can be correspondingly varied.For instance, the turn on characteristic of the switch module can betailored such that it more closely approaches that of an ideal switch.Alternately, the switch module could be tailored to produce a shapedconductive curve.

By configuring FETs 7302 a-n such that one or more of them are of arelatively smaller size, their faster turn on characteristic can improvethe overall switch module turn on characteristic curve. Because smallerswitches have a lower gate to channel capacitance, they can turn on morerapidly than larger switches.

By configuring FETs 7302 a-n such that one or more of them are of arelatively larger size, their lower channel resistance also can improvethe overall switch module turn on characteristics. Because largerswitches have a lower channel resistance, they can provide the overallswitch structure with a lower channel resistance, even when combinedwith smaller switches. This improves the overall switch structure'sability to drive a wider range of loads. Accordingly, the ability totailor switch sizes relative to each other in the overall switchstructure allows for overall switch structure operation to more nearlyapproach ideal, or to achieve application specific requirements, or tobalance trade-offs to achieve specific goals, as will be understood bypersons skilled in the relevant arts(s) from the teachings herein.

It should be understood that the illustration of the switch module as aseries of FETs 7302 a-n in FIG. 73 is for example purposes only. Anydevice having switching capabilities could be used to implement theswitch module, as will be apparent to persons skilled in the relevantart(s) based on the discussion contained herein.

Reducing Overall Switch Area

Circuit performance also can be improved by reducing overall switcharea. As discussed above, smaller switches (i.e., smaller area under thegate between the source and drain regions) have a lower gate to channelcapacitance relative to larger switches. The lower gate to channelcapacitance allows for lower circuit sensitivity to noise spikes. FIG.74A illustrates an embodiment of a switch module, with a large overallswitch area. The switch module of FIG. 74A includes twenty FETs7402-7440. As shown, FETs 7402-7440 are the same size (“Wd” and “1 ng”parameters are equal). Input source 7446 produces the input EM signal.Pulse generator 7448 produces the energy transfer signal for FETs7402-7440. Capacitor C1 is the storage element for the input signalbeing sampled by FETs 7402-7440. FIGS. 74B-74Q illustrate examplewaveforms related to the switch module of FIG. 74A. FIG. 74B shows areceived 1.01 GHz EM signal to be sampled and downconverted to a 10 MHzintermediate frequency signal. FIG. 74C shows an energy transfer signalhaving an aliasing rate of 200 MHz, which is applied to the gate of eachof the twenty FETs 7402-7440. The energy transfer signal includes atrain of energy transfer pulses having non-negligible apertures thattend away from zero time in duration. The energy transfer pulses repeatat the aliasing rate. FIG. 74D illustrates the affected received EMsignal, showing effects of transferring energy at the aliasing rate, atpoint 7442 of FIG. 74A. FIG. 74E illustrates a down-converted signal atpoint 7444 of FIG. 74A, which is generated by the down-conversionprocess.

FIG. 74F illustrates the frequency spectrum of the received 1.01 GHz EMsignal. FIG. 74G illustrates the frequency spectrum of the receivedenergy transfer signal. FIG. 74H illustrates the frequency spectrum ofthe affected received EM signal at point 7442 of FIG. 74A. FIG. 74Iillustrates the frequency spectrum of the down-converted signal at point7444 of FIG. 74A.

FIGS. 74J-74M respectively further illustrate the frequency spectra ofthe received 1.01 GHz EM signal, the received energy transfer signal,the affected received EM signal at point 7442 of FIG. 74A, and thedown-converted signal at point 7444 of FIG. 74A, focusing on a narrowerfrequency range centered on 1.00 GHz. As shown in FIG. 74L, a noisespike exists at approximately 1.0 GHz on the affected received EM signalat point 7442 of FIG. 74A. This noise spike may be radiated by thecircuit, causing interference at 1.0 GHz to nearby receivers.

FIGS. 74N-74Q respectively illustrate the frequency spectra of thereceived 1.01 GHz EM signal, the received energy transfer signal, theaffected received EM signal at point 7442 of FIG. 74A, and thedown-converted signal at point 7444 of FIG. 74A, focusing on a narrowfrequency range centered near 10.0 MHz. In particular, FIG. 74Q showsthat an approximately 5 mV signal was downconverted at approximately 10MHz.

FIG. 75A illustrates an alternative embodiment of the switch module,this time with fourteen FETs 7502-7528 shown, rather than twenty FETs7402-7440 as shown in FIG. 74A. Additionally, the FETs are of varioussizes (some “Wd” and “1 ng” parameters are different between FETs).

FIGS. 75B-75Q, which are example waveforms related to the switch moduleof FIG. 75A, correspond to the similarly designated figures of FIGS.74B-74Q. As FIG. 75L shows, a lower level noise spike exists at 1.0 GHzthan at the same frequency of FIG. 74L. This correlates to lower levelsof circuit radiation. Additionally, as FIG. 75Q shows, the lower levelnoise spike at 1.0 GHz was achieved with no loss in conversionefficiency. This is represented in FIG. 75Q by the approximately 5 mVsignal downconverted at approximately 10 MHz. This voltage issubstantially equal to the level downconverted by the circuit of FIG.74A. In effect, by decreasing the number of switches, which decreasesoverall switch area, and by reducing switch area on a switch-by-switchbasis, circuit parasitic capacitance can be reduced, as would beunderstood by persons skilled in the relevant art(s) from the teachingsherein. In particular this may reduce overall gate to channelcapacitance, leading to lower amplitude noise spikes and reducedunwanted circuit radiation.

It should be understood that the illustration of the switches above asFETs in FIGS. 74A-74Q and 75A-75Q is for example purposes only. Anydevice having switching capabilities could be used to implement theswitch module, as will be apparent to persons skilled in the relevantart(s) based on the discussion contained herein.

Charge Injection Cancellation

In embodiments wherein the switch modules discussed herein are comprisedof a series of switches in parallel, in some instances it may bedesirable to minimize the effects of charge injection. Minimizing chargeinjection is generally desirable in order to reduce the unwanted circuitradiation resulting therefrom. In an embodiment, unwanted chargeinjection effects can be reduced through the use of complementaryn-channel MOSFETs and p-channel MOSFETs. N-channel MOSFETs and p-channelMOSFETs both suffer from charge injection. However, because signals ofopposite polarity are applied to their respective gates to turn theswitches on and off, the resulting charge injection is of oppositepolarity. As a result, n-channel MOSFETs and p-channel MOSFETs may bepaired to cancel their corresponding charge injection. Hence, in anembodiment, the switch module may be comprised of n-channel MOSFETs andp-charnel MOSFETS, wherein the members of each are sized to minimize theundesired effects of charge injection.

FIG. 77A illustrates an alternative embodiment of the switch module,this time with fourteen n-channel FETs 7702-7728 and twelve p-channelFETs 7730-7752 shown, rather than twenty FETs 7402-7440 as shown in FIG.74A. The n-channel and p-channel FETs are arranged in a complementaryconfiguration. Additionally, the FETs are of various sizes (some “Wd”and “1 ng” parameters are different between FETs).

FIGS. 77B-77Q, which are example waveforms related to the switch moduleof FIG. 77A, correspond to the similarly designated figures of FIGS.74B-74Q. As FIG. 77L shows, a lower level noise spike exists at 1.0 GHzthan at the same frequency of FIG. 74L. This correlates to lower levelsof circuit radiation. Additionally, as FIG. 77Q shows, the lower levelnoise spike at 1.0 GHz was achieved with no loss in conversionefficiency. This is represented in FIG. 77Q by the approximately 5 mVsignal downconverted at approximately 10 MHz. This voltage issubstantially equal to the level downconverted by the circuit of FIG.74A. In effect, by arranging the switches in a complementaryconfiguration, which assists in reducing charge injection, and bytailoring switch area on a switch-by-switch basis, the effects of chargeinjection can be reduced, as would be understood by persons skilled inthe relevant art(s) from the teachings herein. In particular this leadsto lower amplitude noise spikes and reduced unwanted circuit radiation.

It should be understood that the use of FETs in FIGS. 77A-77Q in theabove description is for example purposes only. From the teachingsherein, it would be apparent to persons of skill in the relevant art(s)to manage charge injection in various transistor technologies usingtransistor pairs.

Overlapped Capacitance

The processes involved in fabricating semiconductor circuits, such asMOSFETs, have limitations. In some instances, these process limitationsmay lead to circuits that do not function as ideally as desired. Forinstance, a non-ideally fabricated MOSFET may suffer from parasiticcapacitances, which in some cases may cause the surrounding circuit toradiate noise. By fabricating circuits with structure layouts as closeto ideal as possible, problems of non-ideal circuit operation can beminimized.

FIG. 76A illustrates a cross-section of an example n-channelenhancement-mode MOSFET 7600, with ideally shaped n+regions. MOSFET 7600includes a gate 7602, a channel region 7604, a source contact 7606, asource region 7608, a drain contact 7610, a drain region 7612, and aninsulator 7614. Source region 7608 and drain region 7612 are separatedby p-type material of channel region 7604. Source region 7608 and drainregion 7612 are shown to be n+material. The n+material is typicallyimplanted in the p-type material of channel region 7604 by an ionimplantation/diffusion process. Ion implantation/diffusion processes arewell known by persons skilled in the relevant art(s). Insulator 7614insulates gate 7602 which bridges over the p-type material. Insulator7614 generally comprises a metal-oxide insulator. The channel currentbetween source region 7608 and drain region 7612 for MOSFET 7600 iscontrolled by a voltage at gate 7602.

Operation of MOSFET 7600 shall now be described. When a positive voltageis applied to gate 7602, electrons in the p-type material of channelregion 7604 are attracted to the surface below insulator 7614, forming aconnecting near-surface region of n-type material between the source andthe drain, called a channel. The larger or more positive the voltagebetween the gate contact 7606 and source region 7608, the lower theresistance across the region between.

In FIG. 76A, source region 7608 and drain region 7612 are illustrated ashaving n+ regions that were formed into idealized rectangular regions bythe ion implantation process. FIG. 76B illustrates a cross-section of anexample n-channel enhancement-mode MOSFET 7616 with non-ideally shapedn+ regions. Source region 7620 and drain region 7622 are illustrated asbeing formed into irregularly shaped regions by the ion implantationprocess. Due to uncertainties in the ion implantation/diffusion process,in practical applications, source region 7620 and drain region 7622 donot form rectangular regions as shown in FIG. 76A. FIG. 76B shows sourceregion 7620 and drain region 7622 forming exemplary irregular regions.Due to these process uncertainties, the n+ regions of source region 7620and drain region 7622 also may diffuse further than desired into thep-type region of channel region 7618, extending underneath gate 7602 Theextension of the source region 7620 and drain region 7622 underneathgate 7602 is shown as source overlap 7624 and drain overlap 7626. Sourceoverlap 7624 and drain overlap 7626 are further illustrated in FIG. 76C.FIG. 76C illustrates a top-level view of an example layout configurationfor MOSFET 7616. Source overlap 7624 and drain overlap 7626 may lead tounwanted parasitic capacitances between source region 7620 and gate7602, and between drain region 7622 and gate 7602. These unwantedparasitic capacitances may interfere with circuit function. Forinstance, the resulting parasitic capacitances may produce noise spikesthat are radiated by the circuit, causing unwanted electromagneticinterference.

As shown in FIG. 76C, an example MOSFET 7616 may include a gate pad7628. Gate 7602 may include a gate extension 7630, and a gate padextension 7632. Gate extension 7630 is an unused portion of gate 7602required due to metal implantation process tolerance limitations. Gatepad extension 7632 is a portion of gate 7602 used to couple gate 7602 togate pad 7628. The contact required for gate pad 7628 requires gate padextension 7632 to be of non-zero length to separate the resultingcontact from the area between source region 7620 and drain region 7622.This prevents gate 7602 from shorting to the channel between sourceregion 7620 and drain region 7622 (insulator 7614 of FIG. 76B is verythin in this region). Unwanted parasitic capacitances may form betweengate extension 7630 and the substrate (FET 7616 is fabricated on asubstrate), and between gate pad extension 7632 and the substrate. Byreducing the respective areas of gate extension 7630 and gate padextension 7632, the parasitic capacitances resulting therefrom can bereduced. Accordingly, embodiments address the issues of uncertainty inthe ion implantation/diffusion process. it will be obvious to personsskilled in the relevant art(s) how to decrease the areas of gateextension 7630 and gate pad extension 7632 in order to reduce theresulting parasitic capacitances.

It should be understood that the illustration of the n-channelenhancement-mode MOSFET is for example purposes only. The presentinvention is applicable to depletion mode MOSFETs, and other transistortypes, as will be apparent to persons skilled in the relevant art(s)based on the discussion contained herein.

7.7.2 Phased D2D—Splitter in CMOS.

FIG. 72A illustrates an embodiment of a splitter circuit 7200implemented in CMOS. This embodiment is provided for illustrativepurposes, and is not limiting. In an embodiment, splitter circuit 7200is used to split a local oscillator (LO) signal into two oscillatingsignals that are approximately 90° out of phase. The first oscillatingsignal is called the I-channel oscillating signal. The secondoscillating signal is called the Q-channel oscillating signal. TheQ-channel oscillating signal lags the phase of the I-channel oscillatingsignal by approximately 90°. Splitter circuit 7200 includes a firstI-channel inverter 7202, a second I-channel inverter 7204, a thirdI-channel inverter 7206, a first Q-channel inverter 7208, a secondQ-channel inverter 7210, an I-channel flip-flop 7212, and a Q-channelflip-flop 7214.

FIGS. 72F-J are example waveforms used to illustrate signalrelationships of splitter circuit 7200. The waveforms shown in FIGS.72F-J reflect ideal delay times through splitter circuit 7200components. LO signal 7216 is shown in FIG. 72F. First, second, andthird I-channel inverters 7202, 7204, and 7206 invert LO signal 7216three times, outputting inverted LO signal 7218, as shown in FIG. 72G.First and second Q-channel inverters 7208 and 7210 invert LO signal 7216twice, outputting non-inverted LO signal 7220, as shown in FIG. 72H. Thedelay through first, second, and third I-channel inverters 7202, 7204,and 7206 is substantially equal to that through first and secondQ-channel inverters 7208 and 7210, so that inverted LO signal 7218 andnon-inverted LO signal 7220 are approximately 180° out of phase. Theoperating characteristics of the inverters may be tailored to achievethe proper delay amounts, as would be understood by persons skilled inthe relevant art(s).

I-channel flip-flop 7212 inputs inverted LO signal 7218. Q-channelflip-flop 7214 inputs non-inverted LO signal 7220. In the currentembodiment, 1-channel flip-flop 7212 and Q-channel flip-flop 7214 areedge-triggered flip-flops. When either flip-flop receives a rising edgeon its input, the flip-flop output changes state. Hence, 1-channelflip-flop 7212 and Q-channel flip-flop 7214 each output signals that areapproximately half of the input signal frequency. Additionally, as wouldbe recognized by persons skilled in the relevant art(s), because theinputs to I-channel flip-flop 7212 and Q-channel flip-flop 7214 areapproximately 180° out of phase, their resulting outputs are signalsthat are approximately 90° out of phase. I-channel flip-flop 7212outputs I-channel oscillating signal 7222, as shown in FIG. 721.Q-channel flip-flop 7214 outputs Q-channel oscillating signal 7224, asshown in FIG. 72J. Q-channel oscillating signal 7224 lags the phase of1-channel oscillating signal 7222 by 90°, also as shown in a comparisonof FIGS. 721 and 72J.

FIG. 72B illustrates a more detailed circuit embodiment of the splittercircuit 7200 of FIG. 72. The circuit blocks of FIG. 72B that are similarto those of FIG. 72A are indicated by corresponding reference numbers.FIGS. 72C-D show example output waveforms relating to the splittercircuit 7200 of FIG. 72B. FIG. 72C shows I-channel oscillating signal7222. FIG. 72D shows Q-channel oscillating signal 7224. As is indicatedby a comparison of FIGS. 72C and 72D, the waveform of Q-channeloscillating signal 7224 of FIG. 72D lags the waveform of 1-channeloscillating signal 7222 of FIG. 72C by approximately 90°.

It should be understood that the illustration of the splitter circuit7200 in FIGS. 72A and 72B is for example purposes only. Splitter circuit7200 may be comprised of an assortment of logic and semiconductordevices of a variety of types, as will be apparent to persons skilled inthe relevant art(s) based on the discussion contained herein.

7.8 Design of the Filter.

The design of the filter 5726 is determined by the frequency andfrequency range of the desired transmission signal 5714. As discussedabove in sections 3.3.9-3.3.9.2, the term “Q” is used to describe theratio of the center frequency of the output of the filter to thebandwidth of the “3 dB down” point. The trade offs that were made in theselection of the subharmonic to be used is a factor in designing thefilter. That is, if, as an excursion to the example given above, thefrequency of the desired transmission signal were again 910 MHz, but thedesired subharmonic were the 50^(th) subharmonic, then the frequency ofthat 50′ subharmonic would be 18.2000 MHz. This means that thefrequencies seen by the filter will be 18.200 MHz apart. Thus, the “Q”will need to be high enough to avoid allowing information from theadjacent frequencies being passed through. The other consideration forthe “Q” of the filter is that it must not be so tight that it does notpermit the usage of the entire range of desired frequencies.

7.9 Selection of an Amplifier.

An amplifier module 5728 will be needed if the signal is not largeenough to be transmitted or if it is needed for some downstreamapplication. This can occur because the amplitude of the resultantharmonic is too small. It may also occur if the filter 5726 hasattenuated the signal.

7.10 Design of the Transmission Modules

A transmission module 5730, which is optional, ensures that the outputof the filter 5726 and the amplifier module 5728 is able to betransmitted. In the implementation wherein the transmitter is used tobroadcast EM signals over the air, the transmission module matches theimpedance of the output of the amplifier module 5728 and the input of anantenna 5732. This techniques is well known to those skilled in therelevant art(s). If the signal is to be transmitted over apoint-to-point line such as a telephone line (or a fiber optic cable)the transmission module 5730 may be a line driver (or anelectrical-to-optical converter for fiber optic implementation).

1. A system for modulating and up-converting an information signal,comprising: gating means for gating the information signal at a ratethat is substantially equal to a desired sub-harmonic of a desiredfrequency of an output signal, thereby generating a gated informationsignal, said gated information signal having an amplitude that is afunction of the information signal; differentiating means fordifferentiating said gated information signal to generate a harmonicallyrich signal having a plurality of harmonics; and selecting means forselecting at least one of said plurality of harmonics as a desiredoutput signal, said desired output signal being at said desiredfrequency. 2-25. (canceled)